As I see it, the serious candidates in the Republican party are (in no particular order):
1 Marco Rubio (experience: over ten years in congress, can win elections).
You're wrong about Rubio's having "over ten years in congress". Rubio did serve several terms in the Florida State House of Representatives, but he has never been a US Representative and is still a first term senator, having been elected in 2010. He's about as qualified as Obama was when Obama won the Presidency. He's probably unelectable thanks to some stupid moves he's made -- he voted against the Violence Against Women Act.
2 Scott Walker (experience: Governor, smashing unions and winning hard political fights)
George W. Bush used to say "I'm a uniter, not a divider." Scott Walker is his opposite, which leads me to think that he is not electable. Walker is still in his first term and he dropped out of college, which is a big negative (in my view). He was only one semester short of a degree, but he's never bothered to finish? Something's not quite right there.
3 Chris Christy (experience: Governor, reaches across the aisle, achieves Republican goals in a Democratic state).
Christy is a corrupt New Jersey politician. The question is whether or not that corruption will catch up to him before the election. I think it will.
IMHO, Republican primary voters appear incapable of recognizing competency. There are several good Republican Governors out there, but they're not on anybody's radar screen. The Governor of New Mexico is one -- she's in her second term, has apparently done a good job because she has very high public opinion poll ratings, and she happens to be a hispanic woman.... but few people outside of NM (and its neighboring states) have ever heard of her.