Universal Champion: Seth Rollins
Unfortunately, I'm not as confident about this as I was a few weeks ago. As last year should have made plain, we should never be confident about anything where Brock Lesnar is concerned, except of course his ability to win and disappear when he shouldn't.
The fans are still behind Seth Rollins, but the return of Roman Reigns to the picture changes everything, especially now with his acceptance after his cancer scare. There is at least a decent chance that Vince McMahon again decides to revisit the Brock Lesnar vs. Roman Reigns feud. It would be an atrocious mistake which would send Raw back into the void it's been in for the past two years, and guarantee that fans once again turn on Reigns, but the possibility is strong.
Then there's Brock Lesnar's uncanny ability to squeeze Vince McMahon for concessions. That should always be taken into account.
My fingers are crossed and I'm still favoring Seth Rollins, but by a far lesser margin than I was before. Now, I'd only put his chances of winning at slightly over 50%.