I always get black but I've had a black iPhone 4 for over a year and there will be a short release window between the iPhone 4s and iPhone 5 so I thought time for a change and bought the white, I'm glad i did, change is cool.
Both look great, I've got a Black iPad2 so if both are sitting next to each other in a cafe I don't look like a fan boy with matching i's, glad i went with white I also chose it because of Steve, he just passed away and something struck me about the white 4S, kind of reminds me of the first white iPods, that was a great time buying those upgrades every year, if you think the colour of Apple as a company white comes to mind, so Steve this white iPhone 4S 64GB I will proudly use is my ode to you, I wear it and I use it in memory 4STEVE, but come the iPhone 5 I'll go black.