So, I think about this a lot and would be interested to see what other people choose. I also want to get into the full details of this. Why are you choosing the options you are choosing? Why that class? Why that subclass? Why that feat? Why that weapon? Why that spell? Etc. Be detailed or give an overview. 

Given the vast choices and difference in D&D and the Real World, let's establish some rules of this little game. 

You will be the only one with magic/powers/etc. So your 20 in Strength is beyond Olympic level, given that most people in the world will be around 10. Bear in mind the rules on how much you can lift, push and carry with such a score - it's quite above normal. Perhaps not superhuman, but still. It'd get you noticed. Likewise, shooting fire and flying around will gather immense amount of attention. Would you run the risk of breaking this secrecy? Do you think the world will accept your gifted nature or be rather unkind? What about your family and friends?

Official content. Any. Regardless of setting. Just official. Not One D&D or Playtest or UA or Homebrew. With one exception which I'll get to.

ASIs - start with point buy. Doesn't matter what you think they'd be , they'll become these scores. 

Race - Choose any, but think of it as still being human but with that race's powers and abilities. If the feature requires a part of you to match, like wings for an aarakocra then they'll shift into it as necessary or you magically gain them. And it wouldn't destroy clothing or anything. It's magic, it'd be in your favour. Flavour as needed to make it work. 

Background - too many of the official backgrounds use features that are barely useful in D&D and practically useless in the real world. So let's just go with the One D&D rules on backgrounds, with exception of the ASI (as you still get that from your race). So: 2 skill proficiencies, 1 tool proficiency, 1 language, 1 feat (any official), and 50 GP (which can be equipment or the money). Proficiencies and languages will be in addition to what you currently have as a real world person. Languages will be real world languages. Already know English and Spanish, well you could choose French as your "background" language choice and now you know 3. So it's less "background" and more "extra bonuses".

Speaking of Gold -- So yeah, obviously gold is a weird one. Now, I'm in the UK and making the game so we actually have a gold coin as legal tender here. It's not actually accepted anywhere so it being legal tender is mostly pointless, but the precedent is we do have Brittania gold coins, with face value of £100. Most internet forums would put D&D gold as somewhere in the region of £100 to £250 ish, so how about we just say £100, or $100 US, or something. We dont need specifics. So that 50 gp starting gold from background? That could be £/$ 5,000 - be it D&D equipment, modern stuff or just money in the bank. Same with class starting equipment - get the cash or the item, your choice. 

Material Components With Gold Cost - now we established the gold thing, let's say you just can, if preferred, spend the money instead of having the costly material component - even if the money is in your bank. If the spell effect requires the component such as Secret Chest or Instant Summons, the component is created but exists only to serve the spell. You couldn't sell it or use it for any other purpose. This rule also applies to spells replicated using Wish.

Wish - spell replication only. To be clear this is any spell of 8th level or lower, cast as if a 9th level. 

Simulacrum - You can have only one at a time. It can only be of yourself. On creation you must choose what spell slots to give it, otherwise it has none. 

Deities/Patrons/Etc - For sake of simplicity we can say these spells, features, etc work without the need of a deity or whatever. So, you don't need to be religious for the cleric powers, serve a patron for warlock ones, etc. Likewise any spell or feature referring to such will work without such. For example Commune / Contact Other Plane,  is not contacting a deity or planar entity, more like the knowledge comes from the collective consciousness of humanity. Or something. 

Multiclassing? Yeah, go on then.

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Think that is pretty much all the rules needed. 

I'll put my own choice separately.

Honestly, although magic and spells would be fun my go-to answer would probably be Monk, with the powers of one of the flying races because flight would be fun. 

Class/Subclass (Monk (18)/Way of the Shadow) + (Warlock (2)/ Celestial)

-super powerful magic fists (1d10 isnt super impressive in D&D, but compared to a bunch of regular people it would be within insta-kill territory)

-ability to deflect bullets

-quasi-super speed and ability to run across water/up walls. Can also fall from up to 10 stories without being harmed. 

-slower aging and immunity to poisons and diseases (always nice)

-can speak any language

-shadow arts spellcasting would be super fun

-limited teleport is always nice to have

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-celestial healing is nice to have, for myself or to help others

-can use Eldritch Invocations to get Devil's Sight for help seeing in Darkness from shadow magic. Mask of Many Faces could be useful too for concealing my identity. 

Background

Boosting both my Investigation and Perception dont really play into my chosen class, but would be a general quality-of-life improvement in my opinion.

Tool proficiency wouldnt be a big deal, maybe alchemist supplies.  

Languages would basically be an afterthought since I have Tongue of the Sun and Moon

Feat: Telekinetic, because who doesnt like shoving people with their mind. Plus, invisible mage hand is fun. 

Edit: If I were building it off of my existing real-world strengths, I would likely be a transmutation wizard or an artificer, given my scientific background

Yurei, the Alchemist Artificer
Alchemist Artificer 19/Wizard 1
10/16/10/20/14/14
Winged Tiefling

Chosen for a few reasons, but speaking primarily to Cybermind's challenge...

Under the presumption that I am the only person with D&D Abilities, "combat" becomes mostly meaningless.  If everybody else is a generic NPC and I'm a level 20 PC, the only way to beat me in combat is with vehicle-grade weaponry.  I have 103 hit points, the average mook has four.  Antimaterial rifle shots to the head are an aggravation, not a threat.  Beyond that, I am not an Adventurer delving into ancient tombs - I'm Yurei, some hussy living in a Murican suburb working a garbage job to get by.  We can largely forget anything having to do with 'Combat' and focus on what I'd love to be, and what would improve my life and potentially let me not get snapped up and studied by the government/corporations.  And the answer to that is artificer.

Why Artificer, and why the Worst Artificer?
Artificers are masters of making.  They're the Tool Guys, the Inventy Guys, the people who understand creation.  That's an intensely valuable skillset in the modern world, especially for someone like me that already has a basic grounding in electronics.  Take 'basic grounding in electronics', add nigh-superhuman level genius intellect (20 Intelligence), add Tool Expertise so any check I make with a tool with which I am proficient (note: "proficiency" means trained in the tool, which you CAN get post character creation in the modern world through various courses and experience) is absurdly good.  On the presumption that my proficiencies with alchemist's supplies, tinker's tools, smithing tools, and the like transfer to modern equivalents, I effectively become a master engineer overnight.  Once I prove out that knowledge I can name my price, and that's if I deign to work for other people instead of using my excellent-to-superhuman mental stats to start my own businesses and/or sell game-changer innovations to other businesses and become independently wealthy that way.  Alchemist, in specific, means I'm an expert in chemistry and chemical sciences, as well as being able to create Elixirs that are much lower key than "magic walking gun turret" or "combat robot".  

Artificer also allows me to create magic items (and not necessarily just my infusions - for artificers specifically, crafting items is a class feature), which bolsters my 'dump' stats and allows me to use objects that seem ordinary and mundane but which give me an undeniable edge.  When I'm wearing an ordinary set of clothes that just so happens to include a Belt of Hill Giant Strength, invisible Gloves of Thievery to act as an SSI and a spellcasting focus for my artificer spells, a Ring of the Ram as an unremarkable and effectively invisible personal defense item, and whatever else I want that day I have a lot less cause to be worried about my cover slipping.  As well, because all my spellcasting is in the form of creating magic-imbued objects, it's much easier to disguise my spells as simply superiorly clever home engineering and a particularly capable Companion App.  With a careful eye towards selecting spells with subtle effects and being discrete in casting them, the world's utter disbelief in magic will be all the shield I need to keep my powers mostly under wraps.  Unless I do something stupid like use my sexy sexy devil girl Winged Tiefling wings out in the balls-out open, at which point the jig is up anyways and I'm going into (Wo)man vs. World mode anyways.  Which I'm prepared for with Survival proficiency anyways.

There's a million little interactions that make artificer the only possible choice for me, honestly.  Between Enhance Ability/Skill Empowerment, Guidance, and Flash of Genius I never have to worry about failing at anything ever again.  Alter Self means I can escape this awful meat shell I'm stuck in and occupy one I actually like, at least for an hour at a time in the privacy of my own home.  And if everything goes tatas skyward and I end up running from the world, I've got an escape mechanism and nonlethal deterrent in the form of my Fey-Touched spells, giving me a way to use my reserves of magic even without any of my tools.  Which, to that point:

Sacrificing Soul of Artifice (almost entirely a combat feature) for a single level of wizard gives me three additional priceless cantrips, a bunch of additional utility and defensive spells for when things inevitably go south for me, and access to a sixth-level spell slot.  I don't get to consume my infusions to avoid death multiple times a day, but frankly if I'm in a situation where a Death Ward isn't enough I'm probably screwed anyways because it means someone/thing is making a concerted effort to kill me.

But yes.  Depending on the world's overall level of acceptance (which I will assume to be 'absolutely none'), as an artificer with a skoche of wizard I can do almost anything up to and including raising the recently dead, as well as having the absolute best stats (Intelligence is king and no one will convince me otherwise, with above-average Wisdom and Charisma only allowing me to make better use of genius-level intellect) and the best possible Real Life Paychecks class feature in Tool Expertise.  Fabricate allows me to skip the actual crafting and just make something, provided I have the know-how to make it the old-fashioned way, and as an artificer I can switch out which of my gadget-spells I feel like having on the daily from the best prepared-magic list in the game outside a well-stocked wizard spellbook.

The only wrinkle is that my possession of such abilities would prove that possessing such abilities is indeed possible, and as such many in the world would stop at absolutely nothing to learn how to possess such abilities themselves.  Secrecy and obfuscation would be paramount if I wanted to live a more-or-less ordinary life, especially as I am specifically not, at all, set up to be able to deal with other level 20 folks trying to Highlander me.  Ergo Tony Stark rather than Dr. Strange, hide behind Sufficiently Advanced Technology and use my mundane talents to earn my living rather than my secret magic wherever possible.  Doesn't mean I'm not prepared to defend myself, but "self defense" is not the end goal.  Living a splendid life as a sexy sexy devil girl renowned inventor and innovator bucking business trends and doing Good in the world where I can is the end goal here.

So yeah.  Think that's enough to be getting on with.  How's that, Cybermind?

Something to think about.

Quote from Yurei1453 >>

So yeah.  Think that's enough to be getting on with.  How's that, Cybermind?

 
Bloody brilliant! 

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For my choice I was very tempted by Druid. The idea of just being able to be a spellcasting cat for most of the day is incredible. Plus you'd be well equipped to just go "**** society" pick a forest or jungle and go live there. The biggest barrier for a human to do this isn't the big animals but the bugs and parasites because you can be bitten, stung, infested, poisoned or diseased very easily. Druids are mostly immune to all of this. Between actual immunity to all poisons and disease and any "Beast" having to make a save throw 'gainst your Spell Save DC to even attempt anything (bearing in mind that Beast basically means all non-human creatures in the Real World, even the creepiest of crawlies) and you're safe as can be. 

Thing is, I'd go bored. There's not much to actually do out there. So, I'd still want to be part of modern society and watch things, have internet, etc. And the Druid spell list is kinda lacking in versatile options in that regard.

So, I went with mah trusty Wizard class. Lo and behold, Cyb3rM1nd the Wizard.

Race

I went with a Mark of Hospitality Halfling. This is primarily for Innkeeper's Magic and their Spells of the Mark. The Innkeeper's Magic gets me my fave cantrip Prestidigitation. It also gets me an easy, free, cast of Unseen Servant. I be a lazy bastage so it doing my chores is gonna be spiffy - it can do the vacuuming and tidying while I clean with mah Presti-wigglyfingers. If I go out for a meal for some bizarre reason, a respectful "prayer" of Purify -dontgimmegoodpoisoning- Food & Water and I don't have to give a crap -- or at least, not a runny one. 

Spells of the Mark will add some goodies I won't get as a wizzy, like Create Food & Water. I will never need to buy groceries ever again. Yeah, it's all bland, but a bit o' Prestiflavour and I now get to eat the tastiest and healthy food every day. And I can have all mah beefy burgers while technically being a vegan. In fact, I'm vegan plus - not even plants had to die for my food. 

Instead of Common, I put in English. Coz, ya know, dat what I use. Instead of Halfling I put Welsh. Technically my native language, it would be nice if I could actually speak it fluently. 

Background

History and Perception. Maybe this will mean I can say **** off to my glasses. Knowing history is good. Language choice was Japanese. It's a super interesting language, mostly because I watch a lot of anime, and my attempts to learn it fried some braincells - so the option to just know it without the hassle would be spifftastic. For the feat I went... Magic Initiate - OMFG I know, that's a surprise. So I gots me Mending. I also got minor illusion because it can be useful and for my 1st level I went Feather Fall. It's not like I plan to go jumping off cliffs or anything but for a once-a-day emergency I won't need to prep for, who knows? One of those better to have and not need than to need and not have kinda things.

Now to the good stuff. The Class.

I went straight Wizard. I found Order of the Scribes was just going to suit me best. Conjuration was tempting for the many uses of it's 2nd level feature, but for Scribes it had 3/4 very useful features whereas conjuration and all others had either 1 good or 2 ok features. 

Wizardly Quill isn't a super shocking feature but it combines well with other features, I always get access to it, and can never lose it. Never underestimate a pen. That being said, when I mentioned 3/4 really good features, this wasn't one of them. All uphill from here, baby.

Awakened Spellbook - so, changing damage type is useful - I have no offensive spells. I'm a 20th level wizard, I have other solutions for combat and basically immortal by this point so dafuq I need combat spells for? However, I can, once per day, cast any ritual from my book using the normal time. As a full-fledged member of LazyPeeps, I appreciate this. But the main beaut of this feature is I can replace my spellbook for free. The whole thing, not just the spells prepped. Find a blank book summon my quill and write some squigglies for an hour and shebang - fully replaced spellbook. Nothing beats the peace of mind. Also, wonderful news, a spellbook is a spellbook and worth 50 gp. So even if I get a basic blank notebook for a quid and pennies, it will become a spellbook, worth 50 gp. This is important. 

Manifest Mind - so I can hear and see from two places at once and 6 times per day cast a spell from this if within 30 ft of me. So, basically, I can add 30 ft extra range on any spell, even if the spell is actually self-targeting. Hello 60 ft Misty Step. 

Master Scrivener - So I can make a free spell scroll once a day, which lasts a day, and can be a 1st level spell cast as 2nd level, or 2nd level cast as 3rd level. Free spellcasting is a big YAY.

One With The Word - So if I know I be about to get a big owwie, make a Manifest Mind thingymabob, and then when the owwie happens it becomes a non-owwie. Imagine being told the plane is going down and you can just shrug, sit calmly and sip your tea. Then just walk or swim away, skippedydoodahday. Death Ward on steroids to cast for free. Thank you.

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All in all it's a pretty decent subclass for the leisurely life I wanna have. It's basically the subclass of convenience and peace of mind - and that totes be in my style.

Most of the spells are fairly obvious. Some are not so, like transmute rock and move earth, wall of stone. stone shape... So the eventual plan is get a plot of land and use these spells alone with fabricate if needed to make a home. Borrowed Knowledge can give me masons tools and whatever else I'd need. Disintegrate and Move Earth are useful for precise digging. I'd also invest in Solar Panels and then use Wish to Replicate Continual Flame cast on those panels. Since "Solar" is a misnomer and they get energy from ANY light, bathing the panels in a permanent, endless, source of light (without heat) means I'm basically creating a small source of infinite, safe, energy. With exception for a line for internet I'd otherwise be entirely off grid. With no rent or mortgage. No need for food shopping. No electricity bills. 

To get the money, I can use Wish to Replicate Glyph of Wardings to store Enhance Ability and Skill Empowerment as needed. Buy raw materials. When all ready, cast Borrowed Knowledge (because my Spellbook counts as the "book worth at least 25 gp" -- see why the "spellbooks are 50 gp" is important?) to get prof and then use Fabricate. One day I might make paintings. Another I might make small wooden toys. Or furniture. Or clay pottery. Or... Ya get the idea. The spell says you can benefit from your tool proficiencies but not that you need to roll them so once can assume you just take the max. But even if it's a roll, it's gonna be good. You're using magic, so it'd be your spell mod, or at least a mental stat - like Cha for an artistic painting. Well my minimum then, with double prof (skill empowerment) is +13, +1 cha, and min 1 on die so 15 is my minimum. Bearing in mind, I'd have advantage and Halfling Luck. So, I'm guaranteed to make something of good quality. Sell. Profit. Weeks of creative work, done in a matter of minutes. On top of my reduced food bills and full time job.

Advanced Tip. If I wanted to stay home and play games or something - I can use the cantrip versatility feature to swap a cantrip for Encode Thoughts then  Wish up a Simulacrum. Sim-Me goes to work. When Sim-Me comes back, we can both use Encode Thoughts to basically transfer Sim-Me's memories to me. I can then Dispel Sim-Me. Also noting I took Keen Mind - so, yeah. 

Wish-Clone for immortality.

Demiplane for safe places.

Magnificent Mansion for decadence or to just say ****-off to the world (make Demiplane, cast Mansion inside - live forever in a different plane of existence. When ready to return, there's Banishment). Mag Mansion won't have internet so living in it fully is pretty much a "nope to the world" vibe. Or, ya know, when I need to lay low for a bit because being a middle-aged lookin' dude at 247 years old might raise a few suspicions. 

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Now relying on Clone-Immortality isn't the best for everyday stay-safe and Distintegrate isn't something I'd ever use for combat. I'd prefer a lack of the punchies. So that's where things like Calm Emotions, Suggestion and Sleep come in.

And since I don't wanna end up dissected, worshiped, hated, etc I'll be keeping Modify Memory on standby in case anybody sees some magic they shouldn't.

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I think about this way too much.

20th level Wizard (Transmutation)

Transmute is the most useful out of combat but with the new spelljammer book I can do something no other person has done before.

Explore the galaxy with Air Bubble.

Clone myself in a demiplane to live forever.

Travel faster than light with teleport. 

I'll be on the closest M-class planet if you need me. Every now and then I'll pop back to earth to conjure up some gold for my family and use my 14th level feature to fix any serious injuries or diseases.

I have all the time in the universe to go and do/see anything and I can bring some people with me. Any takers?

I would be a hill dwarf cleric for 1 reason. Automatic divine intervention. Also extra hit points.