I'd consider Rand Paul and/or Bernie. I do believe them coming together and running could be just the transitional 3rd party this country is in dire need of. Them coming to an agreement upon a platform to run on in 2016 would be epic on a world stage.
Or do you mean of the establishment candidates? Honestly I like John Kasich. I personally worked with him in DC under Bush Sr. and Clinton. There's no question in my mind that he is the most competent and honorable of the bunch, D or R. Although he is a bit more of a social conservative than I'd like to see calling the shots on Pennsylvania Ave.