There are so many trap matches here where one guy or team SHOULD win that I think the WWE is going to have to think outside the box and throw in some surprises. The downside of that, of course, is that such swerves often suck.
For example, Bray Wyatt needs to go over against Cena, even if he loses the match. Cena coming out on top really does nothing for him, it would just be a big set-back for the Wyatt Family's momentum. The standard thing to do here would be the Family interfering but this is Wrestle Mania--the usual interference angle would, and should, be considered a lame cop-out. They're going to need to be clever with this match or it could blow up in their faces.
Rollins/Ambrose should win the titles pretty soon but they might prioritize their split with Reigns before that. This could be a drama match with a swerve.
The Bryan situation is hella tricky, especially. Bryan should win both matches, he really should, but that would be so obvious that it would almost be a disappointment. There HAS to be some kind of craziness involved. Like Punk coming back and giving DB a GTS so he loses, something like that.
That's why I'm not really going to make any predictions, as I think there will be a lot of side-action with these matches and a good dose of controversy. Still, if I had to bet, I'd say that Batista walks out with the title.