Appealing to the base solely isn't going to win this election for the GOP.
The fact of the matter is the Dem base is now larger than the GOP base in this country thanks to changing demographics. I am not referring exclusively to voter registration status, but rather, political beliefs.
So, for the GOP to win - they need to be able to win "purple states" and appeal broadly to swing voters, particularly white suburban females who live in the midwest and mid-atlantic.
For those reasons, I believe John Kasich, former Indiana governor Mitch Daniels, and Nikki Hailey would be among the better options.
Larry Hogan - Governor of Maryland - is quite popular in his state, but he is currently fighting cancer. At the moment, he's cancer free, but I believe his health history likely would preclude him from seeking higher office anytime soon. More:
http://www.albanydailystar.com/health/m ... 10517.html