Have you seen both in an Apple Store ? I was sold on the black until I saw it in the flesh , the black SS looked kinda cheap, maybe it was not dark enough , the silver SS looked much better and everyone agreed. The best Looking in my opinion was the silver SS with bracelet, my work mates aslo thought so.
Under the case, the extreme lighting makes it look gunmetal in color. On the wrist and under normal lighting, it looks jet black.