Usually some sort of hybrid class: Shaman, Battlemage, Arcane Warrior, Paladin, Red Mage. Whatever you want to call them. Alternatively a pure caster and rarely a Rogue. Almost never a Warrior.
I do reroll quite often though, hardly ever being happy... not that I play much MMO. I was really content with my 30/0/21 Shaman though, back before TBC in WoW.