It would be interesting to have different varieties of Armor models (ie. different helmets, armors, kneepads, shoulder pads, visor etc etc) and be able to customize the color of your armor as well.
These features would obviously unlock as you "rank up" in the game by playing or getting achievements after doing some set of challenges or so. This feature would some what add more reason to play the game as players try to rank up to get some customization. This is just an opinion though so don't take it so seriously