#1 Finn Balor
Finn Balor has to be the most underused performer on the WWE roster. The former Universal Champion has proven time and time again, with impressive performances against the likes of Seth Rollins and Roman Reigns, why he should be in the main event title picture, but the WWE seems to insist on keeping him floating around in upper mid-card obscurity.
Balor needs some sort of change if he is ever going to hit the heights he is capable of in the WWE, and while he may be super-over with the fanbase, a heel turn could be the be an option for the Irish superstar.
Balor has excelled as a heel in the past, giving fans some of his best work during the original Bullet Club run in NJPW.
Teaming Balor up with Lesnar and Heyman would instantly establish him as one of the company's top heels, and he could easily work with Heyman while Lesnar is away doing his thing in UFC.
This could also lead to a feud between Finn Balor and Brock Lesnar a little later down the line.