#2 Roman Reigns
Baron Corbin is one of the best, if not the best heel in WWE at the moment. The people who don't think Corbin is good are simply wrong. That being said, I am done with any storyline involving Corbin with a group of wrestlers, supporting him antagonising the top face of the brand.
On the flipside Roman Reigns has spent too long not doing all that much and WWE need to start heating him up for WrestleMania, and getting Reigns back up to the top of the entire men's division where he was before he had to take time off.
For that reason, Reigns absolutely needs to best Baron Corbin in their match at Royal Rumble and then move on to bigger and better things heading into WrestleMania, because he's a legitimate star and it's time.
Plus, if Reigns is going to win the Royal Rumble, as he's a strong contender to do so, it would cheapen the achievement if he loses a match to Baron Corbin earlier on in the evening.