Although he's been 17-ing with his swing this year and has generally sucked, I'd be hard-pressed not to put my money on Padraig.
If not Padraig, then I'd go with Stricker if he has at something like 30/1 or worse. That guy is too good not to have a major yet. He's played well at the Open recently as well.
And, for long shots, either of the Argentine golfers. Romero or Cabrera.