my predictions:
DEFENDERS:
Fighter - good at keeping enemies near himself because monsters that ignore him trigger many of his abilities
Paladin - good at keeping enemies near himself with divine magic (compulsion spells), not as durable but can heal himself a little, also better protected against magic but has a code of conduct
STRIKERS
Rogue - runs across the battlefield and stabs people in the face. Best at finding weak spots, best mobility in game, good at disarming and dodging traps
Ranger - more mobile than you average hero, but not so much as the rogue. Typically sneaks and shoot enemies with ranged weapons. Has an animal companion that helps in combat a little. Best at spotting traps and ambushes.
Sorcerer - teleports across the battlefield hammering enemies with touch spells. Has good magical defenses but they wear off quickly so he can't take much punishment. Can use spells to find traps and destroy them without any finesse.
LEADERS
Cleric - divine master of boons and curses that, in a time of need, can replace a controller for a few rounds with reduced efficiency. Casts best healing spells, medium armor only.
Warlord - charismatic warrior who makes others better at what they do (increasing daily uses of abilities, giving extra actions, etc.). Can also lead by example: with certain abilities, when he does something, his allies can do the same thing even if they normally can't. Can replace a defender if necessary, for few rounds.
CONTROLLERS
Wizard - arcane master. Controlls the flow of battle with area damage spells, time altering magic (haste, slow, time stop), and illusions.
Druid - nature mage. Controlls the flow of batlte with area spells related to weather (fog), plants (entangle), and summoned animals/elementals.