Cena vs Bryan at Summerslam 2013 for the WWE Championship.
Even though Punk vs Lesnar had the better build and was the better match that night imo, having Lesnar simply defeat an ever-resilient underdog babyface like Punk (and without any championship on the line to boot) would have been a huge downer and kind of weird for a headline match at Mania. There's certain criteria that has to met in order to pass for a Wrestlemania main event, and Bryan winning his first WWE Championship by defeating the face of the company clean in the middle of the ring is definitely more worthy of closing out a Wrestlemania than the former. Of course, HHH and Orton turning heel and cashing in on Bryan is kind of a downer too, but at least it has the aspect of two guys turning heel and siding with one another for the first time in several years and also would involve the first-ever MITB cash-in at a Wrestlenania. Then again, if we're being absolutely technical, the question is simply which match would make for the best Wrestlemania main event, which means I can choose to ignore what happens after the match if I so desire and simply pretend the night ended with Bryan standing tall as the champion.
