Depends what you want to be, Here are the 4 choice that you may pick from. (don't pay any attention to our Raid classes as we are doing updates to everything.)
Warrior: Can be Tank, Off Tank, MDPP (Melee Damage Per Post)
Guardian: Off Tank, MDPP (Melee Damage Per Post)
Sorcerer: AoE (Area of Effect), CC (Crowd Control), SDPP (Spell Damage Per Post)
Reiki: SDPP (Spell Damage Per Post), Healer.