Hard to say. What we're seeing is unprecedented.
My guess is that Trump wins it on the Republican side. The only other one I see as having a chance is Cruz, but I can't quantify his chances, especially against Trump. I don't think anyone else matters. Bush is done for, Rubio will expertly play the part of the oiled-up Cuban boytoy at a pool party, Christie is the fatso in the "NEW JERSEY SHORE YO" wife-beater shirt that sits near the buffet and tells everyone that he didn't eat any of the chips from the now empty bowl, Kasich is the guy that keeps yelling "Hey, guys! The Governor of Ohio is on TV!" and Ryan is well... not going to win.
On the Democratic side it's hard to say. If we weren't deep into the twilight zone, Clinton would be the expected candidate on the (D) side of the ticket. I think right now it's 50/50... people keep dismissing Bernie Sanders and he's still around and polling strong. Of course, the same could be said of Howard Dean before his campaign imploded. Hillary is still holding on to her pantsuit pants and pretending that she's the clear and undisputed front-runner. Martin O'Malley is busy taking his jacket off, rolling his sleeves up and getting ready to pack his campaign up.
Bottom line... who the fuck knows? What I can say with certainty is that neither Trump nor Cruz are candidates I'd cast a vote for in the general election and I'd never vote for Hillary or Sanders. So that leaves me with the option of hitting the gym and training legs and skipping the general, or voting for a third-party candidate. So leg day it is.
I'll predict the obviously ridiculous matchup of Trump v. Sanders, a fight that will be long-remembered as the Battle of the Hair.