I think John Kasich is by far and away the best guy of anyone who's running, but his chances of being elected aren't much better than CurtOne's.
I think Cruz would be better than Trump, but I still couldn't vote for him. I think he's a snake oil salesman and a charlatan. The government shutdown was nothing more than a reckless act of self promotion on his part, and that automatically disqualified him in my eyes. I also have a lot of trouble with anyone running as a "constitutional" conservative who supported what Kim Davis did in Kentucky. It's all well and good if you want to run against gay marriage and play to the evangelical crowd, but don't portray yourself as a "strict constitutionalist" and still stand on the same stage with someone who defied a constitutionally decided upon Supreme Court ruling. He knows how to play to his crowd, and he's pretty much the ultimate in the say anything/do anything to be elected politician. I seriously even think he'd make Nixon look like a pillar of ethics if he got elected.
Rubio is my backup pick if/when Kasich loses whatever viability he has left, but I can't say I'm really in love with him either. Still, he's a better person than Trump or Cruz, there's no way I can vote for another Bush, and he's less likely to say something he'll regret later than Christie.
It's a really ugly field of candidates we have to choose from this year.