The white one is 1 millimeter thicker then the black. In my country the black iPhone cost 140 US$(1000 kr, I'm from Sweden) then the white one. Make a poll of the thred with two answeres, 1. white, 2. Black and people will vote, much easier and more people will answer!
IMO, you should get a white, they are rarer and sexy, but watch out for stains