I went with Romney.
The Idi Amin Jr. contingent will savage Hillary if she contests on 2012. By the time the general election rolls around, the RICKAMAVEN types will be voting for Green Party / Nader candidates as opposed to voting for the Clintons again.
Gingrich is damaged goods. He is a fair-weather conservative who breaks commitments when he thinks no one is looking.
Palin - despite what everyone thinks - will not run for President. She is WAY more effective as a fundraiser and "spoiler" (for lack of a better term), and she knows it.
Idi Amin Jr. is toast. They can stick a fork in the chicken to see if it is done.
That only leaves Romney.