So... Have you decided on what Job you'll be using for each Role for the Role quests?

[Allegor]

Tank: GNB
Healer: SGE, unless I don't like it, then I revert back to WHM
Ranged: DNC
Caster: RDM
Melee: DRG or NIN I guess, maybe MNK

[Bright-Flower]

PLD and DNC as they're the jobs I play the most.
Reaper and Sage probably to try the jobs out. Unless I just, really really end up hating them from levels 70 to 80 in which case I'll drop them for dragoon and white mage.
Red mage for caster.

Crafters/gatherers will probably be Armorer, Carpenter, Alchemist, Miner and Fisher.

[Sathona]

Tank: Gunbreaker
Healer: Sage
Melee: Reaper
P. Range: DNC or MCH [hard to decide]
Caster: Black Mage

[aveyond-dreams]

Summoner, Astrologian, Reaper, and Paladin.

[SilverObi]

I max out every job so won't really be an issue but for sure PLD RDM WHM DNC as those are my "mains" for each role. MNK has been my go-to melee since 1.0 but reaper is looking pretty cool...

[weebtext]

Tank: Dark Knight - Even though it didn't get anything new and flashy, it's still my favorite tank.
Healer: Sage - New healer go brrr
Melee: Reaper - I'll be doing the MSQ with it and hopefully maining it if I enjoy it enough.
Ranged: Machinist - Shotgun. That's the only reason.
Caster: Black Mage - I'm looking forward to seeing how the new stuff fits in the rotation.

I'll eventually be levelling everything to cap but those are the ones I'll be doing first.

[StriderShinryu]

Caster: RDM
Tank: GNB (PLD?)
Melee: DRG (MNK?)
Ranged: DNC (MCH?)
Healer: AST

Caster and Healer are 100% locks. I do also really enjoy BLM so it may actually end up being the second class overall that I get to 90 but, well, it's not RDM. AST is the only healer I really enjoy playing, and I do like it quite a bit overall.
For Tanks, I enjoy how GNB feels to play the most by far, but I've always loved the PLD aesthetic more so if EW PLD plays more like a class I enjoy, I may go PLD.
For Melee, I'm almost guaranteed to go DRG. Something about EW SAM just kind of bores me, but new MNK could jump into first place here depending on if I like the changes or not. I'm not sold so far but I am interested.
For Ranged, I'll probably just go DNC because MCH bores me to tears and I really don't enjoy BRD at all. But MCH is so braindead that if I'm not enjoying the ranged story anyway I may just go MCH so I can sleepwalk my way through it.

[nebby00]

Tank: Completely dependent on which relic weapon I get done first, so it's a toss up for me between WAR and PLD. Hopefully PLD though considering it is the class that Endwalker shows off in the trailer.
Healer: AST! ...At least until I unlock Sage. I love AST to death, especially when I spam Gravity, however with Sage being able to heal by doing damage, it definitely has caught my attention!
Melee: This one is a toss up between DRG or Reaper. Hoping that Reaper will be just as fun as DRG.
Ranged: DNC, no questions asked. Love DNC, plus I do like how both the male and female artifact gear looks for level 90.
Caster: RDM... because it's the only caster I have at 80 right now, and I usually like being the one to raise people if things go horribly wrong in fights, which I am anticipating they will on release day/week.

Still working on leveling all of my battle classes, I had made decent progress so far c:

[EorzeaHero69]

For me:

Paladin for tank.
Scholar and Summoner for healer and caster.
Dragoon for melee.
Dancer for ranged.

[ChazNatlo]

Caster: Summoner.
Healer: Scholar.
Tank: Dark Knight.
Melee: Reaper likely, unless I take the extra time before launch to level my Dragoon again. Maybe Samurai, if I'm feeling particularly industrious.
Ranged: Dancer.

Most of them are because they start at higher levels so it'll take less time to level them.