In the end, your going to be the one deciding which color to buy, however I will chime in with with my 2 cents.
I currenetly have the white/black combo, although I'm using a 5 and not a 5s. It looks sharp, better then the bumper I was using from Target, IMO. I constantly get compliments on the contrast. Plus, this case looks and feels premium, like the iPhone and unlike the iPhone 4 Bumper (and I loved the bumper).
I hope Apple does something of the like later this year with the iPhone 6. I'll probably get another white phone/black case, unless they have gold or don't have white or gold (then I'd get Space Gray).