I originally had the Black 920, but only because I wasn't patient. The rest of the colors were sold out in my state, and I was more concerned with WP8 than the fact it was a Nokia device (my 900 was Cyan--made me a fan of Nokia). I inevitably swapped it for Red, as I want to stand out in a crowd. I want people to notice me. So far the glass finish is a little slippery if you set it on your lap, but otherwise I think I've come to the right decision as to which one I was supposed to end up with. Currently I'm using the Cobalt/White theme and really love it.
That being said, the Black 920 is one heck of a phone. Ultimately, the fact that it is a 920 trumps anything about what color it is. Sure, it matches every color (except brown... ugh, who uses brown?!), but I've never been one to swap color that often. I usually just swap colors per phone (this is my sixth WP, so it's my sixth color). I digress. Like many have said, the bonuses from the device itself are just too good to make the color a concern: sensitive screen, NFC, wireless charging, and hands down the best phone camera you've ever used.