Personally I would love to see diversity in builds.

Would be nice if we could get that through ability enhance materia, since gear wouldn't be so reliable due to it always getting replaced, which would make abilities more unique especially through a slight change in the abilities animation and color.

It would also be nice to have single player type "limit breaks" and we could instead just call them an "overdrive" or "quickening" and have variety to choose from that would fit our playstyle such as having a big hitter, multiple hits, and so on.