Its difficult to go with an open-ended question like that. Different people like different fish. I suggest looking at places like liveaquaria or bluezoo, pay attention to the suggested minimum tank sizes and see what YOU like. Run your list by everyone to be sure it will work. There are lots of great fish that will work for a 75...smaller Tangs (Kole, Tomini, Two Spot, etc not Blue/Hippo, Yellow, etc), dwarf or Pygmy angels, several wrasses, some anthias, basically there are lots of great options.
. Do 75 if given the choice though.