#2 - Shinsuke Nakamura
Perhaps the most natural summer opponent for Daniel Bryan is Shinsuke Nakamura, who could be set to win the WWE Championship next week at Money in the Bank when he meets AJ Styles in a Last Man Standing match.
Should he emerge with the belt, it's hard to imagine him going through 2018 without butting heads with Bryan. The pair already have some history, with the then-SmackDown GM being the one who helped introduce him to the main roster last year.
In terms of match quality, you would expect this to be a winning combination. Both of them are brilliant technicians with the ability to tell compelling stories in the ring. Provided they get enough time - 25 minutes, at the very least - this should be absolutely awesome.