Given that list and given Cheney's health, I'd have to say it would be Gingrich.
Baggage and all.
I'm betting that when the dust settles, that the one's remaining standing will be the heads of the Moderate Wing and the Compassionate Conservative wings of the Party...that is, the standard bearers of the McCain wing and the Bush wing of the party.
John McCain will head the McCain wing.
Frist or Allen will head the Bush wing, and Pres. Bush is very beholden to Frist.
It'll come down to McCain or Frist. I see Condi Rice as the kicker VP candidate who will go with either candidate in order to blunt the female/black advantage that Hillary brings to the game.