Really depends on the art style and setting, and also what exactly you are going for. I haven't played your game but from the screenshots it looks like a multi-canon parody game so the obvious choice to keep you busy for ages would be canon alternative costumes. If you want to do a themed update there's usually a bunch of core outfit tropes to follow e.g. just type "sexy Halloween" into amazon's search. Then you can try and appeal to specific fetishes but that might be risky if you don't know your specific audience well enough. Will they prefer a bunny girl outfit over shiny latex? Gas mask or cat ears?
Frankly unless a character is designed around a certain style I find most typical "outfits" disappointing and an erasure of individuality. Sleazy clubs stuff girls in bunny suits, housework has to be done in a French maid outfit, apparently streetwalking has a uniform and "sexy" underwear always is red/black/pink frilly lace. Why even bother to have distinct characters at that point unless the core of your game is running a maid café or the like?
So TL;DR: poll your actual player base rather than randos in General Discussions.