Riley, Paul, or Johnson the next president?

Who defeats Obama in 2012? The only 3 capable of beating President Obama are two libertarians, and one republican. Rand Paul could win since he isn't part of the system as hes only been in elected office for a month, but it also is a disadvantage since he isn't experienced. Gary Johnson would be a solid choice also with no baggage and wouldnt be so far right but that could hurt with the religious right and cost him votes. Riley is Reagan-ish and had a very good run as governor but is not well known outside of the state of Alabama. Either three I feel would win in 2012. Paul would win by the narrowest margin. Johnson would win by a comfortable margin. And Riley could hammer Obama in a landslide. So who do you think republicans will choose of the three listed? And please, spare us the answers of the hacks known as Palin, Romney, and Huckybee.