I'm about to start a campaign with 5 friends (6 players + 1 DM)

2 of them are completely new to D&D, one has a little bit experience and 3 of us are veteran RPGer with some D&D experience.

We're about to start a new campaign and here's what we have so far

- 2 Warlock (Vet and little experienced player) (Celestial and hexblade)

- 1 Circle of the moon druid (vet)

- 1 Ranged Ranger (beastmaster with primal compagnion) (new player)

That leaves a new player and me.  I'm expecting the new player to pick someone not too complicated, like no magic so Fighter (but he played one in  our intro campaign so may need a change), a Barbarian or a Rogue.

I would like to pick something to balance our group but I can't decide.  Arcanic magic would really help but we would lack frontliners (especially if he goes Rogue).  I was considering  a Twilight Cleric if he goes Barbarian/Fighter but I feel if he goes rogue, I would be better with tank/defender, like a Paladin or some kind of fighter.

What would you guys advise?

Just play w/e you want. 6 players is already a hefty boost on the players side as far as power goes. I’d go something simple yet effective to streamline the game a bit with that many players, especially new players.

you all starting at level 3 already?

Yes, we're all starting at lvl 3

A soul knife might be cool to play. It would cover slot if skill proficiency and maybe a few tool proficiencies.

a kenku, half elf, human variant, or any race with multiple tool or skill proficiencies can go a long way to cover for the party. Psi-bolstered knack is pretty amazing since the use isn’t wasted if the check fails.

Agree on the Soul Knife thing though I am gonna through in Artificer for your consideration, Amorer or Battlesmith could easily fill up the Frontline while having decent Arcane support as well as being a respectable skill monkey, also depending on how you do stats and what you roll Bladesinger could be quite helpful.

The druid and hexblade are likely to be frontliners so with a barb you would not need another.

If you want to go for party balance I would go int based to help with all the history and 8nvestigation checks. If you want to go frontline armorer and bladesinger would work.

Quote from Jegpeg >>

The druid and hexblade are likely to be frontliners so with a barb you would not need another.

If you want to go for party balance I would go int based to help with all the history and 8nvestigation checks. If you want to go frontline armorer and bladesinger would work.

 I think that the Armorer would be my choice here. Being able to change from front liner to ranged on a short rest (as long as you have Smith's tools in hand) will give you some good flexibility. 

Bladesinger is less of a front liner and more of an option to be an off "tank" for the ranged members, especially as you continue to level past 6th.

The other new player opted for a swashbuckler.  As much as I love bladesinger, I think a fighter or a paladin will work better for this team.

Artificer may work, I never bothered to read the rule since I dislike the concept.

MY 2CP would be to suggest maybe Eldritch Knight for your fighter.  It would give you the usual solid base of a Fighter and slowly bring Arcane magic to your group.  I have one I created and at 8, dipped into Wizard, mainly for the Ritual casting abilities.  He has amazing utility skills and spells and can use Shield as required, to avoid some damage.  Unique spin on the "Wizard" of your group, filling 2 roles moderately well.

Quote from Falwith >>

MY 2CP would be to suggest maybe Eldritch Knight for your fighter.  It would give you the usual solid base of a Fighter and slowly bring Arcane magic to your group.  I have one I created and at 8, dipped into Wizard, mainly for the Ritual casting abilities.  He has amazing utility skills and spells and can use Shield as required, to avoid some damage.  Unique spin on the "Wizard" of your group, filling 2 roles moderately well.

 Eldritch knight is a wonderful option. It’s interesting since, like the arcane trickster, it kind of gets periodic upgrades when new wizard spells are released.

if you do end up playing an Eldritch knight, I would advice you to mostly try to focus on reaction and bonus action casting. This preserves the fighters action to make use of extra attack.

the new hexblood is nice with the hex spell added, along with various other magical freebies that replicate spell effects an Eldritch knight wouldn’t normally have access to. 
elves and half elves can be dreadfully powerful when they make use of elven accuracy and the shadow blade spell. The damage can be amazing along with the situational advantage and high number of attacks. It rivals sharpshooter and greatweapon master builds with much less feat investment.

The other thing you can do with Eldritch Knight spells is go for long duration or out of combat spells. Disguise self and Identify can be every bit as useful as Shiled and Absord Elements.

Have a word with the Mood Druid about the possibility of getting Mage Armor, depending on when he wild shapes and what into that could really help his AC. (Of course it would mean him not wearing armor when not in WS so depending on his Dex he is likely to have lower AC with Mage armor than without if wielding a shield)

I've been toying with EK build since yesterday.

Got one build with a Glaive and Polearm master which seems to be the one doing most damage with straight up attacks and ignoring the cantrips

I've also made  sword and board one which use booming blade or green-flame blade based on the situation.

I'm currently looking at a shadow blade build but we so few spell slots, I'm currently finding it underwhelming since it cannot use cantrips.

Quote from DeamonQCX >>

I've been toying with EK build since yesterday.

Got one build with a Glaive and Polearm master which seems to be the one doing most damage with straight up attacks and ignoring the cantrips

I've also made  sword and board one which use booming blade or green-flame blade based on the situation.

I'm currently looking at a shadow blade build but we so few spell slots, I'm currently finding it underwhelming since it cannot use cantrips.

 Shadow blade with elven accuracy deals more damage than polearm master and greatweapon master combined, with or without advantage. But it is limited by 2nd level spell slots, which at level 7, an Eldritch knight would have two of.

A dexterity based Eldritch knight also has the versatility to use a ranged weapon like a long bow if that becomes necessary, something a polearm master would have an issue with when fighting airborne enemies.

and then if the knight somehow gets a better weapon than shadowblade, which is unlikely, then they can change fighting styles and potentially make use of fog cloud and blindsight to generate advantage that way while maintaining incredible defenses.

Hum you are correct, I forgot to apply the stats modifier to SB damage in my calculation.  I'm still worried by the spell slot limitation though,  until level 13, I'm unlikely to have enough slot to use in every encounter of a single day.  But it's worth considering.

I think some sort of monk,  maybe way of the four elements as you get many close range and long range range attacks and you can do a dex or strength based monk

Oh, Hi friend. Don't forget that monks are fairly decent at lower levels as well. Something like that would be good for the new player I think. Also don't forget about the unarmoured defence part!

sorry, i am still new to this forums concept as well as the monk class. I haven't experimented much which the monks yet and mostly just skim the details.

How does unarmored defense work again?

All good friend.

This is how it works:

While not wearing any armour or a shield, a monk has AC (Armour class) equal to 10 + DEX Modifier + WIS Modifier

with the tortle or warforged races that increase AC the monk would also get even tankier which each level, plus the other benefits of the previously mentioned races...

As well as the fact that yes, the higher the level of the monk the better he/she is.
Any more questions?

ok thanks but why tortles and warforged 

Good question.

So for Tortle:

They have natural weapons (Which I don't know but they could be empowered with ki by counting a s an unarmed attack, please anyone correct me if I'm mistaken) and has the ability to hide in the shell adding extra +7 AC, but at the cost of movement deficiency.