QFT.
For me, personally, the biggest PITA enemies...flying enemies. :smallsigh:
As Maya, or Axton, not bad to deal with them, as you can either phaselock them(Either to stun to kill or keep damaging.) or turret blast them.
And as Gaige, simple as pie-Release Deathtrap, then laugh.
But as Zer0...cripes...you have to chip damage them, because none of the specs help at all-Kunai don't help when they don't change direction mid-flight(and the enemies do), MMF is useless on aerial enemies, and Critical Ascention sucks in general.
And in TVHM, Where Angels Fear to Tread is awful! :smallfurious: I'm only level 44(as Zer0), and I've been avoiding most sidequests and the DLCs because I want maximized level 50 rewards from them, but all the enemies are between levels 45-47, and they keep killing me, wasting my money, and exploding my patience. :smallmad: