In my opinion, Kasich is the only candidate (on the Republican side) that acts like a President. Trump does his name-calling bit, Cruz attacks Trump calls him a liar, and Rubio, while he hasn't really done any name-calling, he has made a couple immature remarks. Having said all that, I'll give a list of why I don't like each candidate.
Kasich ~ Most of his policies are great; I just don't like how he supports CommonCore.
Rubio ~ He's made several immature remarks about the candidates, otherwise he seems fine.
Cruz ~ He's always attacking Trump, trying to team up with Rubio, and frankly, my gut tells me he's a phony.
Trump ~ His attitude and the fact that he isn't real specific on his policies.
If I heard a little more on Trump's actual policies, and liked what I heard, I'd support him. See what a businessman can do for the U.S. If not Trump, then Rubio, as he seems somewhat genuine. The thing with the Senators is that "they supported this bad bill" or "were against this great bill" and you aren't sure of their real record of voting in the Senate.
Anyway, just my two cents on whom I like.