Yes, I can.
OP's til the nerf in 1.1.1 - Stealth, Still do tons of burst damage and knock down, and still can kill within 3secs, and area stun.
Sorc's - Damage, Heal, Sprint, and Shield. Nothing Mitigates their damage, plus, spamming Project/Lightning w/ slow with no DR is stupid.
Arensal Mercs - Constant spamming of 1 ability (tracer missile) with great damage without having to worry about overheating compared to their pyro counterparts which can not spam incendiary missile (300-400 damage and 1k dot) because of the differences in heat consumption. The stacking of armor penetration with tracer missile then heat seeker to do tons of damage. Their shield ability while being 1 button menace.
Next in line - Marauder dps/evasion dps comabt mechanic. dps/combat stealthing. Followed by Assassin/Shadow - opening/kd dps