The only melee dps that is unbound to positional requirements for standard rotation is rogue/ninja, but even then if you aren't in front of or behind an enemy you lose certain perks to either Suiton+Sneak Attack or Suiton+Trick Attack.

However, dragoon also had it's positional requirements loosened not that long ago, most you'd have to deal with is standing to the rear for +50 initial impact potency on Chaos Thrust, and standing to the flank of an enemy for the increased potency to Ring of Thorns from Heavy Thrust.