Sorry - I read "Unsexiest Woman Alive" and I assumed it was a vote for which of these women was the least sexy, so I voted Madonna. I've never liked her.
Britney still has potential.
Sandra Oh isn't what I would consider ugly. She's not hot, but she's OK.
Amy Winehouse - I really don't know anything about her, so I can't really comment. Really bad pic, though.
Sarah Jessica Parker - eh. I have zero interest in her, but I have nothing against her.
That leaves Madonna, who I just consider brutally hideous. She does nothing for me physically.