Bryan winning the title in a victory that is anything less than 100% clean. If Cena wins, I can at least somewhat accept that because there's no way they put Bryan in a story line with not only Cena but the McMahon family and HHH only to then cool off on his push afterwards. Thus, I would assume that Bryan's eventual title win would be built up longer to happen at a later date, maybe even Wrestlemania (although I'm skeptical they could hold off that long, especially with Vince believing in the "strike while the iron is hot" philosophy.) But if Bryan wins the title in a flimsy ending, then that would piss me off. The first time a person wins the world title should be special. I'm think of when Austin won his, when Rock won his in a brilliant double turn that no one saw coming, when HBK won his in the "boyhood dream that came true", when Mankind won his on Raw in a rather memorable and epic moment, etc. Tonight is the perfect setting for that kind of moment for Bryan. Don't fuck it up with any sort of screwy ending where it looks like Bryan shouldn't be champion because Cena had him possibly pinned while the referee was knocked out or distracted or whatever.
I'd rather not see Punk defeat Lesnar since I don't want Lesnar taking another loss without at least getting another victory on his record as well. And Lesnar losing means the feud is over. There's no reason to have a rematch if Punk comes out on top the first time.
AJ/Big E winning would also piss me off.