I have had both. Personally, I probably prefer black, attractive timeless aesthetic, and all of that. However, when I recently bought a refurb 80GB in a hurry - I was travelling abroad for several months a day or so later and I had no option but to buy a silver model as the black was not available at such short notice - I have come to really like it hugely as it is such a superb iPod (great capacity, excellent battery). So, performance is what matters at the end of the day. However, it's your call.
Cheers and good luck