Silver wheels can look good on black, especially if you have silver window trim or silver kidneys to match.
Silver or anthracite will also accentuate your low profile tires. Wheels that are too dark "blur the line" so to speak. If a low profile sidewall is something you like, keep that in mind.
I agree with most replies though, Anthracite is the way to go. You still have contrast between the wheel and the tire and a more aggressive look, but your wheel wells don't become black blobs. In my opinion, black wheels rarely look better than the gun metal/anthracite alternative.