#2 Shawn Michaels
According to multiple reports, it seems like Shawn Michaels is finally going to return to the ring at WWE's upcoming show in Saudi Arabia on November 2. Of course, WWE hasn't officially announced his in-ring return, but most people are expecting it to happen.
Whether or not he returns for the Saudi Arabia show will probably have no impact on the pop he'd get if he returned as a surprise in the 2019 Royal Rumble. WWE did want him to come back for the 2017 Rumble, which took place in his hometown of San Antonio, Texas, but he obviously refused their offer.
If he does wrestle in Saudi Arabia, then he might be willing to do more matches, which could lead to a surprise appearance by HBK in next year's Royal Rumble match.