He sounds extremely impressive in any public interview. In addition to his conservative appeal, he sounds knowledgeable on any domestic and foreign policy issue I have heard him discuss.
I doubt he will ever get the nomination, assuming he wants it. The interviews I have heard can't even be called trial balloons, and I haven't heard that he has even explored putting together his organization. It's getting late for that if he wants to make a serious run.
The other three on this list will break my heart if they get the nod. I work fairly hard for my BPOU in my Senate District in Minnesota. My heart won't be in it if we have to start trying to help one of those other three.
The one guy I could get enthusiastically behind, who has started the feeler process, is Ted Cruz.
Ben Carson is no fan of the Second Amendment.