I liked Mitt in 2008. I liked Hunter, Thompson, and one other I can't remember better, but between McCain, Huck, and Romney I went Romney.
But I don't think he can win a primary or the general. Not in 2012 or ever. He's got too muddled a history with his governorship in MA to be viable in the primaries, especially after all this health care reform stuff we've been going through and his moving over the years on abortion positioning. I still think he'd make for a great cabinet member or special advisor on business, fiscal policy, etc.
Huck... he's something of a big government republican and he's was way too lax on pardons and commutations while governor. I just can't see my way to supporting him.
Rudy is out. I like his style, but he's got baggage and his poor showing in 2008 will hamstring any follow up attempt.
Paul Ryan's really making waves with this health care debate. Mike Pence has risen to high visibility too. I'm a fan of Thad McCotter, though I don't think he's interested in higher office. Rubio down in Florida is generating some buzz, but I don't think he'll be viable in 2012, more like a possible 2016 contender if he proves himself out. Bachmann is a bit too much of a firebrand to be viable nationally. Carly Fiorina has possibilities for 2016 (maybe 2012 if she loses her race this year and gets her game together quickly, no more Demon Sheep ads).
Bit too early to declare favorites, but I'd bet Pence or Ryan take a stab at a run in 2012. Maybe Boehner too.