Honestly, I just love new dances. The more exaggerated or goofy, the better! Or some that are genuinely kind of cool, like "the running man".

I just find those fun to pop out if someone is AFK, or for taking screenshots after a clear.

I also wouldn't mind some Job-specific ones, liked a "bored-job" emote. So a MCH might goofy around, pretending to quick-draw at make-believe enemies around, while DRK might lean on their sword, clearly bored, and just playing with a little dark-magic with one of their hands.

My two cents!