Rollins vs Owens sounds great, but I'm not sure Rollins is established enough yet sadly. And Owens definitely isn't. It sucks because I always campaign against having old-timers in the Wrestlemania main event after all these years, but before we can move on from that I feel like these old-timers need to put over a new generation and establish them as stars. If that makes any sense. To me it would feel strange to have a Wrestlemania main event between two guys who hadn't been on that level before.
For that reason, I feel like the main event almost needs to have John Cena, Brock Lesnar or (now) Roman Reigns in there to give it that bit more legitimacy. Guys like Triple H or Undertaker technically fit this role too, but I just really don't want to see either of those guys in that kind of spot.
The Shield triple threat would be a great main event actually. That's probably what I'd go for. I've been flabbergasted by their failure to go with that match for a major show yet. Hopefully people haven't forgotten about the history between these guys by the time they finally do the match. If I was going with the Shield in the main event, I'd have Rollins be the Royal Rumble winner and the babyface for the match. Reigns would be the heel champion, after holding the belt for a year. Ambrose would be the tweener.
A heel Reigns against a face Rollins or Ambrose individually could be good too. Usually I'd prefer it as I'm more of a fan of singles matches, particularly for Wrestlemania. But the Shield dynamic does make the triple threat interesting in this case.
Face Rollins against a heel Lesnar is another match I'd love.
I think Sami Zayn vs a heel Reigns or maybe a heel Lesnar would be the best Wrestlemania feud in years, and I desperately hope it happens. But Wrestlemania 33 might be a bit soon for that. I think Sami can be a great main event babyface, but he does work best as an underdog character so you can't push him too hard too quickly or he loses part of what makes him special.
It's a pity that what we'll probably get is Roman Reigns vs John Cena.