Having not played a rogue in many years, I find myself needing one. It will begin at level 5. I'd like to make a professional burglar and would appreciate some suggestions.
Tabaxi Thief is probably a good place to start. Tabaxi grants you free Stealth and Perception proficiencies, darkvision, good ability score bonuses and the ability to double your speed for one turn if you get in trouble. The Thief subclass gives you really strong bonuses to climbing and jumping and the ability to use sleight of hand, thieves' tools or objects as a bonus action.
Arcane Trickster would also be a strong contender, since it gets a lot of utility spells and an invisible mage hand.
Tabaxi Thief is probably a good place to start. Tabaxi grants you free Stealth and Perception proficiencies, darkvision, good ability score bonuses and the ability to double your speed for one turn if you get in trouble. The Thief subclass gives you really strong bonuses to climbing and jumping and the ability to use sleight of hand, thieves' tools or objects as a bonus action.
Arcane Trickster would also be a strong contender, since it gets a lot of utility spells and an invisible mage hand.
If we're sticking to rogues, I'm leaning towards arcane trickster.. Spells like spider climb, disguise self and minor illusion can be super useful when breaking into a building. It's true that the thief climbs faster, but if you're breaking into a place, speed often won't really matter.
Arcane Trickster is nearly impossible to beat, because you can bring a Familiar along to take the Help action on your thievery and provide other benefits - if you take an owl, which is generally just the best familiar, you can use the owl as a night-vision telescope to excellent effect, as an example. Critically, you can pick locks from 30 feet away from the lock. However, AT is highly dependent on a variety of GM rulings - they rely on many illusion spells, and they have an interest in trying to cast spells Stealthfully, neither of which have a whole lot of RAW support. There's yet another discussion in the rules forum right now about Invisibility, for example.
I agree with posters above that entering buildings through windows or chimneys is critical for burglary. Accordingly, you'll want a fly speed or a climb speed (thieves get a climb speed) or a teleport, but 5E rules mean Rogues are notoriously awful climbers - gone are the days when a climb speed made you better at not falling, so even with a climb speed, it just means when you pass your Strength-based Athletics check, you get to climb faster. That means fly speeds (tiefling, aarakocra, aasimar if you don't mind being well-lit during your flight, which you should mind as a rogue) and teleport (eladrin, shadar-kai - both are elf subraces; the eladrin can teleport more often, so that would be my go-to) are particularly compelling. The fundamental problem you need to solve is that all burglars need dex for stealth and thieves tools, int for investigate, and wis for perception, which means it's a really big ask putting much investment into the strength stat or the athletics skill. I seriously doubt you can actually make a tabaxi thief who's genuinely good at both burglary and climbing and jumping. Alternative means of movement that don't require any strength or athletics solve the problem neatly. If you're not a race with flight, but you have consistent access to water, an AT with Shape Water can solve the mobility problem by making a ladder out of ice at will. You do not want to be called upon to make Athletics checks if you can avoid it.
Note that Soulknives can teleport, but not until level 9, which is why I haven't suggested them. Phantoms can literally fly through walls, but not until level 13, so same deal there. Likewise, Swashbucklers actually get good at climbing, unlike Thieves, but not until level 13, and depending on your familiar and your GM, an AT with a Familiar can do the same thing at level 3, albeit with a much more complicated action economy. If you had more levels to play with, all of those subclasses would be immediately more tempting.
If you want to multiclass the rogue to get better at burglarly, Guidance is the number one thing you want to pick up. That's available from any Cleric, but Peace gets you Emboldening Bond, which stacks; Artificers have it, and so do Divine Soul Sorcerers. All three of those options will hurt AT spell slot progression if you're an AT. Warlock won't, so if you climb to Warlock 3, Pact of the Tome will give you Guidance, while Warlock 2 will give you Devil's Sight. I don't know of any Warlock subclasses that directly benefit burglary at level 1, but Genie at Warlock 1 will permanently buff your Sneak Attack by adding your proficiency bonus to the damage. It's slightly nerfed in that Genie damage won't work on AoO Sneak Attacks, please note, but for a ranged build, that's not concerning.
There are various other ways to multiclass to get better at burglarly, depending on your plan - for example, 2 levels of wizard can make you a conjurer, which means all you need to do is see a key once to manifest that key as an action, with the crippling downside that the key emits (dim) light. As a druid, as soon as you get wild shape you can turn into a spider, which is absolutely flawless at climbing - a GM asking a spider to make an Athletics check to climb is violating the RAW - and the utility there is obvious. You can also turn into a giant wolf spider, but having a bigger body can make infilitration a lot harder. Both spiders have no rules for spinning webs, so you'll need to ask your GM. If the target building is home to a child, you can also turn into a mastiff or cat out the gate and attempt to infiltrate by looking cute. If you have a GM who's ever even heard of cats, you may be able to persuade your GM to buff the cat stat block so you can see in the dark and climb things (if you do, I recommend removing their bloodhound-grade noses; you may also need to make a Wisdom save to avoid sitting in any empty boxes you find, if your GM has a sense of humor).
Having not played a rogue in many years, I find myself needing one. It will begin at level 5. I'd like to make a professional burglar and would appreciate some suggestions.
Tabaxi Thief is probably a good place to start. Tabaxi grants you free Stealth and Perception proficiencies, darkvision, good ability score bonuses and the ability to double your speed for one turn if you get in trouble. The Thief subclass gives you really strong bonuses to climbing and jumping and the ability to use sleight of hand, thieves' tools or objects as a bonus action.
Arcane Trickster would also be a strong contender, since it gets a lot of utility spells and an invisible mage hand.
The Forum Infestation (TM)
Tabaxi are perfect cat burglars. I agree with IC.
I have a weird sense of humor.
I also make maps.(That's a link)
If we're sticking to rogues, I'm leaning towards arcane trickster.. Spells like spider climb, disguise self and minor illusion can be super useful when breaking into a building. It's true that the thief climbs faster, but if you're breaking into a place, speed often won't really matter.
Arcane Trickster is nearly impossible to beat, because you can bring a Familiar along to take the Help action on your thievery and provide other benefits - if you take an owl, which is generally just the best familiar, you can use the owl as a night-vision telescope to excellent effect, as an example. Critically, you can pick locks from 30 feet away from the lock. However, AT is highly dependent on a variety of GM rulings - they rely on many illusion spells, and they have an interest in trying to cast spells Stealthfully, neither of which have a whole lot of RAW support. There's yet another discussion in the rules forum right now about Invisibility, for example.
I agree with posters above that entering buildings through windows or chimneys is critical for burglary. Accordingly, you'll want a fly speed or a climb speed (thieves get a climb speed) or a teleport, but 5E rules mean Rogues are notoriously awful climbers - gone are the days when a climb speed made you better at not falling, so even with a climb speed, it just means when you pass your Strength-based Athletics check, you get to climb faster. That means fly speeds (tiefling, aarakocra, aasimar if you don't mind being well-lit during your flight, which you should mind as a rogue) and teleport (eladrin, shadar-kai - both are elf subraces; the eladrin can teleport more often, so that would be my go-to) are particularly compelling. The fundamental problem you need to solve is that all burglars need dex for stealth and thieves tools, int for investigate, and wis for perception, which means it's a really big ask putting much investment into the strength stat or the athletics skill. I seriously doubt you can actually make a tabaxi thief who's genuinely good at both burglary and climbing and jumping. Alternative means of movement that don't require any strength or athletics solve the problem neatly. If you're not a race with flight, but you have consistent access to water, an AT with Shape Water can solve the mobility problem by making a ladder out of ice at will. You do not want to be called upon to make Athletics checks if you can avoid it.
Note that Soulknives can teleport, but not until level 9, which is why I haven't suggested them. Phantoms can literally fly through walls, but not until level 13, so same deal there. Likewise, Swashbucklers actually get good at climbing, unlike Thieves, but not until level 13, and depending on your familiar and your GM, an AT with a Familiar can do the same thing at level 3, albeit with a much more complicated action economy. If you had more levels to play with, all of those subclasses would be immediately more tempting.
If you want to multiclass the rogue to get better at burglarly, Guidance is the number one thing you want to pick up. That's available from any Cleric, but Peace gets you Emboldening Bond, which stacks; Artificers have it, and so do Divine Soul Sorcerers. All three of those options will hurt AT spell slot progression if you're an AT. Warlock won't, so if you climb to Warlock 3, Pact of the Tome will give you Guidance, while Warlock 2 will give you Devil's Sight. I don't know of any Warlock subclasses that directly benefit burglary at level 1, but Genie at Warlock 1 will permanently buff your Sneak Attack by adding your proficiency bonus to the damage. It's slightly nerfed in that Genie damage won't work on AoO Sneak Attacks, please note, but for a ranged build, that's not concerning.
There are various other ways to multiclass to get better at burglarly, depending on your plan - for example, 2 levels of wizard can make you a conjurer, which means all you need to do is see a key once to manifest that key as an action, with the crippling downside that the key emits (dim) light. As a druid, as soon as you get wild shape you can turn into a spider, which is absolutely flawless at climbing - a GM asking a spider to make an Athletics check to climb is violating the RAW - and the utility there is obvious. You can also turn into a giant wolf spider, but having a bigger body can make infilitration a lot harder. Both spiders have no rules for spinning webs, so you'll need to ask your GM. If the target building is home to a child, you can also turn into a mastiff or cat out the gate and attempt to infiltrate by looking cute. If you have a GM who's ever even heard of cats, you may be able to persuade your GM to buff the cat stat block so you can see in the dark and climb things (if you do, I recommend removing their bloodhound-grade noses; you may also need to make a Wisdom save to avoid sitting in any empty boxes you find, if your GM has a sense of humor).