I had the black version first and exchanged it for the white version (warranty replacement), and I'm glad I did. Black is beautiful, don't get me wrong. However, beings that the phone is a dust magnet (thanks to the screen protector), the dust was definitely a lot more visible. On the other hand, the white version doesn't nearly look as dirty, and I love the smooth back in contrast to the textured on on the black version, definitely looks more premium.
At the end of the day, it will come down to preference.
LG Nexus 5 / Unlocked / Rooted / CM.11
ASUS Nexus 7 / Unlocked / Rooted / Stock ROM