I've been white with my last two phones (white 4s, white/silver 5s). Because I'm looking at going to the 6s+ I'm considering going back to the black front, as from the display models of the 6+ I've looked at I tend to like it better at that size with the black front. However, I'm still a little torn, since I do like the silver back over the space gray back, though of course it will probably be in a case 99% of the time.
Luckily I'm not due for my upgrade until November, so I can wait a little longer before I have to make my decision.