Lots of ideas I have often hoped for being mentioned. All Gender large size would be great but I would also love a tiny which is smaller than anything we have now (antman). Love the idea of back robot, demon, etc. The 2 head and 4 arms is a idea that really need to be looked into. How about wheels, tracks, hover as part of the foot design? Or animated robot parts, like gears turning, antenna broadcasting. Select main hand and/or off hand weapon when not in combat!
Insect parts, tentacles, lots of different animals.
Some power customization: SS Hurl being able to select present as all the items thrown would be great for my Santa character.