#3 AJ Styles
We've seen Daniel Bryan and AJ Styles face each other on the post-Wrestlemania edition of Smackdown, however, the match ended when Shinsuke Nakamura attacked both men. Styles and Nakamura will likely end their WWE Championship rivalry in a Last Man Standing match at Money in the Bank. The winner of this match could go on to face Bryan at Extreme Rules and/or Summerslam.
The two ROH alum may have been in a WWE ring opposite each other, but they didn't go all out during their bout. They might be saving some things for a rivalry in the future. It could be coming, and it could be for the WWE title. Daniel Bryan has not received a world championship match since he was forced to vacate the title in June 2014.
AJ's reign as WWE Champion has been disappointing, because of authority drama, an overcrowded title scene, and a pair of inconclusive match finishes. It must be noted that his first WWE title reign was much better than this. The Phenomenal One would likely be the de-facto heel in a title program with Bryan, without undergoing a full heel turn. This is also another match that would light the WWE up with its brilliance, and give Summerslam their annual Match of the Year candidate.