Warlock and Hunters for big deeps.
Shaman and paladin for buffs.
Shadow priest for mana.
I’ll play hunter like I always have. Don’t care if there will be more of them now. I believe a lot of people will find the micromanagement, ammo, pet food, rotation and “mediocre/difficult PvP life” off-putting.
I think there will be more fury warriors and rogues than we think, since people will realise that the doomsayers are wrong about the potential of these two dps classes in raids.
Anyone that wants to come to raid, has some gear and know which buttons to press.
Alliance will need lots of shamans, while Horde will want some Paladins. Aside of that each class can find a spot. Meme-meta would stack warlocks and hunters by a lot but gearing that will be a nightmare and lots of rage quits.
Druid isn’t that popular, shadow priest is a mana battery so few are nice…
Shamans - you’ll find people wanting a Shaman in each group to make use of Bloodlust/Heroism and totems and Resto Shamans are the absolute best group healers.
Warlocks/Hunters for DPS as players will stack these knowing they have the highest damage potential in TBC.
Not worth mentioning Tanks as you’ll only bring 2-3.
If you want a class that will not have a problem finding a raid spot I still stand with Shaman being that class.