I'm definitely attracted to Caucasian more so than Black or Asian.
If we're going to go into specifics on ethnic hues then I suppose my perfect color would be the average Caucasians skin color, not ghost white, nor tanned, but leaning toward the ghost white a bit.
Second would be Asian, not as in the subcontinent like India and the Middle east. There is something inherently cute about them, again I wouldn't like them to be too white or too tanned. And this may be a racial stereotype but I feel like Asian women have the best relationship ethic around... Maybe just me being selfish.
Third would be black, I've had more black sexual partners than I have white, and I can honestly say that it really depends on the person. It sounds horrible but I only find a black person truly attractive if they look like they could be white, and have physical features typically found on white or Asian ethnicity... Dunno why, I just don't find the typical black woman very attractive, out of all of my friends that fit this, I never look on them as women, only friends.
My absolute undesirables would be that of the Asian subcontinent, Indo-Asia and the middle east. And Latino's. Women falling under the Asian subcontinents appearance often makes me feel repulsed, I have never, ever met a woman from that region that has reached the age of 30 without looking like a cross between a mottled boar and Cthulhu the dark one. I have never had any desire to become romantically involved with that ethnicity. I'm sure there are exceptions, of course there are, but not for me thank you.
Latino's? I've just never been interested in them. When all my friends show me pictures of a 'hot Latino girl' I literally find nothing hot about that. Perhaps it's my Ye Olde English deep rooted yet subconscious hatred for anyone with Spanish decent, but I dunno. Not my cuppa' tea.