The gravity part isn't really true, especially on expert mode even with post Moon Moon gear.As for which pillar I found to be easiest, definitely Vortex. The gravity-beam is annoying, yes, but Vortex enemies are TERRIBLE at capitalizing on it. Most of the time, it's actually BENEFICIAL for me. I get free infinite hovering left and right to shoot everything like a maniac. How this is supposed to be a debuff is beyond me.
If there happen to be more than 2 storm divers in expert mode on-screen and you get hit by the alien goop, they'll just shotgun you into another dimension because they shoot they sit horizontally next to you and you can only hover horizontally. Aka 100% accuracy for them which means 100% certain death for you. They also happen to have 1600 HP.
It's harder to get to that point in normal mode since the debuff is shorter and the Storm Divers deall less damage and have less HP, so you can somewhat out-DPS them.
But in expert mode you're pretty much ed, and the hornets are tanky as hell, so they turn into even tankier queens.