#1. Stay on RAW: Baron Corbin
Baron Corbin seems like the next opponent of Roman Reigns if rumors are to be believed. Even though this might look like a stale feud, there is a little bit of backstory surrounding the proposed angle.
When Roman Reigns announced the return of his leukemia, Corbin allegedly asked the WWE Universe to move on from him and also allegedly stated that he hoped Reigns never came back.
After Reigns did return, Corbin was asked about his comments and he stated that his words were due to stress and then went on to warn Reigns to stay out of his way.
There is some ember here that could be fired up and that seems like the path WWE might choose right now. The company might have paved the way for the same by pitting Reigns against him in a 3-man tag team match on RAW.
Also, given that Corbin is one of the most hated Superstars in the WWE right now, putting Reigns against him will automatically generate cheers for the Big Dog.