They both look great. However, I got black for the following reasons:
1. You can see the sensor (proximity/light) and camera more visibly on the white while it's more hidden on the black.
2. When the screen is on, the black hides the border of the display so it looks like edge-to-edge glass on the screen.
3. The black won't show dirt. There is plastic between then glass and the steel band that wraps around the screen. This can get dirty.
HOWEVER, the white WILL NOT become yellow overtime as it's behind glass.
Also, the black shows more fingerprints more easily.