I am going with a donor who has strawberry blonde hair (natural color is red, but she's got highlights) and hazel eyes, and I have brown hair and hazel/brown eyes. There is some sort of resemblance there anyhow, even if not exact.
That said, when looking over the donors, my thought was also about giving the baby the best chance. There were other donors with coloring more similar to mine, but they were heavyset, etc.. I just want the baby to have the best shot, IMHO.
Plus like everyone else has said you have no idea how the genes will mix, none! You could have a bio child that looked nothing like you, you just never know.