I would say body attribute sliders (height, weight, build, bust, etc...)
But even if they just gave say 3 possibilities per attribute I'd be happy. So if your normal human male is 6' in game, make the 3 options be 5'-8", 6', and 6'-4", so you don't end up with extreme cases.
Just make sure male tauren start out at the highest setting for their race and can only go shorter.