Guliani. I've seen McCain a few times in person and he paces like a caged animal when the camera isn't on him. He has major issues from his imprisonment in Vietnam, and who wouldn't. But he clearly doesn't have the temperment to be president. Also, he's ugly.
I think Romney stands a chance.
You know who I adore is Duncan Hunter but realize he has little chance.
Also his health problems are worse than is known. He would not survive his first term.