Close, but no cigar. According to OkCupid[1]―and data mined from its users―the most "attractive"―in this case, measured by messages from previously unknown users received―pose for men is not smiling and not looking at the camera, and for women is "flirting" and looking at the camera (although in both cases smiling gives "above average" attractivity).

[1] http://blog.okcupid.com/index.php/the-4-big-myths-of-profile..., "Myth 1"