I honestly don't remotely want anything that switches our animations out with others. I have no intention of Full Thrusting on my Monk or Aeroing on my BLM. I see no benefit whatsoever, only really messed up battlefield tells. Augment them, perhaps, but then we might as well actually have differing abilities to go with the modified or new animations.
I wouldn't mind some additional stance choices though. Though I may be one of the few people to find DRK's Fenestra guard fairly practical (aside from the part where it doesn't actually thereby perform any counterattacks), Cloud's stance would be a nice touch, especially if I were to say, swap into it only when in Grit or only when out of Grit, either way.