I'm going to do the alternate outfit 1 from Dissidia, I'm thinking, just because the wig I have is so vibrant. Since it's so close to her regular one I may end up going all the way and eventually doing both.
But besides from Terra, I'm not sure who else.. I've tossed around Celes' Sprite version, Rosa, Rydia.. but I don't know.. I'm sure one day I'll end up doing everything!