My concern is how these guys come off on TV. We saw Perry's poor performance in the debates. I know he blamed the pain meds, but I have never seen him do well in debates here in Texas either. Doesn't mean he wouldn't be a good president, just that he may be preceived as 'spacy' on TV. Rand Paul projects a sort of goofy persona, IMO. He has a weird quizzical look on his face when he speaks. Cruz, however, comes off as supremely confident, is fast on his feet, and seems to thrive on adversity.
Just remember how these guys are going to be portrayed on SNL, Jimmy Fallon, etc in addition to MSNBC, CNN.