I had black, now bought white.
I just bought a 32GB White on PAYG. My 3G is black. I had two reasons for choosing the white, one being that I really like how unusual it looks, and the other being that I still have 5 months of contract to go on my 3G and will be using them both. I wanted to be able to tell them apart without having to stop and check the storage capacity. For me only the 32GB makes sense, as my 3G is full to bursting point even though my media library is small.