I first had a Black ip5 and loved its nice bluish-black metal case. I thought the black front behind the glass was kind of boring, but overall loved the stealth bomber look of the phone as a whole.
When a friend wanted to get his ip5 and the only option was white, I offered up mine and switched to white because what the hell. Well, I'm very happy with the white now. I have an ipad3 in white and I think they go well together. Thats not a compelling reason to go white, but it was a factor for being willing to do my friend the favor to get him his black ip5.
If I had to do it all over again, I'd probably pick white as I just like it so much. I still like the black ip5, but have no regrets. I bought the Elago Outfit (black on black) and just love how it "goes" with the white ip5.