One of the things about conservativism is that we also prize competence and experience. Presidents need to have significant Executive experience, or we will get... well, the same kind of incompetency and embarrassment from the last guy we put in who had less than a full term in the Senate under his belt. No thanks.
I like Rubio alot. I think he could be President and win. But Reagan wasn't great only because he was a conservative - he was great because he had also run California.
We need a governor. McDonnell is pretty much toast from the gifts' scandal, so that leaves Perry, Jindal, or Walker. Perry ran last time and made himself look like an idiot on national stage. Unless he is a helluva lot more erudite now (and I would sincerely doubt that), there is no way we want that guy trying to convince the American people that he knows how to put our house back in order after the last few years. That leaves Jindal and Walker - both of whom have impressive reform records, but neither of whom is really a "national face" right now. Jindal had one national speaking gig and screwed it up a bit, but not enough to have left an impression on anyone except the junkies (like us). Walker would pretty much guarantee mass cranial-explosion among the public union and their support sector; which would probably help him a lot in the primary, and be (at best) a wash in the General. He also comes with a lot more name-recognition and built-in support networks, especially with the Tea Party types, who enjoyed him winning repeatedly in Wisconsin quite a lot. Jindal is likely to generate less controversy, but might have the more impressive record overseeing the recovery from Katrina and BP Oil Spill. And imagine the fun of telling Democrats that every time they criticize him it's because they are racists .