I'd say a properly built assassin can out damage a warrior vs a single target. A warrior is going to be more survivable, though. In the AoE category, I'd say an elementalist, followed close behind by a ritualist would be the case. There are certain circumstances where a specific build under specific conditions would out damage one of the professions mentioned, but we're talking general trends here.
For instance, if we're talking extreme cases, I'd say a MM necro w/ 10 minions and some other buffs would out damage any other profession. Similarly, a ranger specced a certain way could probably inflict very high DPS vs a single target through a combination of conditions, raw damage, and other bonuses through use of crit-chance increasing skills, etc.
Warriors have the highest sutainable DPS vs a single target. Wars also have nice AoE dmg with Axe builds and the right secondary to bost it.
Eles/Rits are the best at AoE dmg thought Necros and Rangers can deal good AoE with the right build in the right locations.
Personally if your looking for lots of numbers poping up go either War or Rit, depending on if you like to be up close and personal or stand back and rain down destruction!
I guess the real question is... do you want to be a melee character (i.e., warrior) or a caster? If you want to bash things over the head for damage, then Warrior is your best bet - I hear they are quite fun to play ^^ If you want to, say drop flaming rocks on someone's head or create giant blasts of lightning, then you should look more toward Ele or Rit (Rit being extremely versatile because you can also make a Rit Lord build that is super-protection or a healing build if need be).