I honestly don't know how far right Rubio is. I think he's pretty standard republican, which is obviously right of center, but I don't think Rubio is an extreme manifestation of right wing politics.
Paul was always the guy I wanted, but he was never going to get elected. I'd love Kasich, but that's not going to happen either. Even though I am actually very concerned about the practical outcomes of some of Bernie's more extreme leftist positions, the truth is that Washington is so gridlocked that I doubt he'd be able to accomplish much of the things on his furthest-left-leaning agenda. Within that context, I would gladly vote for Bernie over Hillary, Trump, and Cruz, because I think he is a truly decent man, someone who is honest and stands by principles, and someone not so pig headed as to be unreasonable. I'd vote for Hillary ahead of Trump or Cruz; Trump because he's a lunatic narcissist, Cruz because he's ideologically dangerous.