My opinion, the best way to speed run in Aurum Vale is having all DPS be Monks and take down the last boss extremely fast.

Right now, because of Cutter's Cry's setup, it is convenient to have Warrior/Black Mage over other DPS until Chimera due to getting mobs into one spot and AoE'ing them all at once. I will say on the Princess fight, we always have at least one DRG in our party, who is always ready to take the Guard down quickly, and almost always succeeds in that. DRG does real well on Princess because they can still dish out nasty damage on the Princess while being able to sustain TP to take down the Guard immediately when the Guard pops. The problem with Warrior (assuming you are not tanking the Marshal or Princess) is that there is always a chance that your WS's are not ready for use. Warriors gain TP a lot slower.

For Chimera himself. Technically the best way to take him down is having melees in your party, Monk especially. If you are able to Dragon Kick that tail off, Chimera really is a pushover for melees, since they can dish out more damage on him than Black Mages. On Chimera between Warrior(DPS) and MNK/DRG, MNK/DRG have a big advantage over them.

So basically, Monk and Dragoon have better single target DPS than Warrior. Dungeons just really call for more AoE damage.