Well, it can't be Cruz because he is Canadian born, only revoking citizenship in 2014. And Rubio couldn't even carry his state. Kasich is the only one who polled consistently trouncing Hillary in the general. Plus, carrying Ohio is a big deal apparently.
So, if the GOP is going to select a winner...someone who can actually carry the general, then it really is a process of elimination. Kasich isn't a puppet. His grit and "in-your-face" ism is appealing. A Mitt Romney type isn't going to cut it. Nor a McCain. Too puppety. To establishment.