I was talking to Brett Slatkin about authorship and he mentioned the Google Consumer surveys offers an A/B image survey that would be perfect for Authorship profile photo optimization.
You also get geographic/demographic breakdowns so I suspect that it's a good deal more informative than the OK Cupid bestface system.
My problem with surveys is that what people say they'll click or appeals to them can differ from what they actually click when they aren't thinking about "I'm taking a survey"
Mark Traphagen, Jun 06 2013 on 1500wordmtu.com