#3 Baron Corbin
Baron Corbin, in the words of JBL, is a future WWE champion, and I agree, but just not yet. He's shown the level of improvement in his in-ring ability and his promo skills, but still isn't the finished product he is capable of being.
If he goes to RAW, he will get the required amount of time to grow as a dominant force. He could go on a series of squash matches, building up his credibility just like Braun Strowman, and once he is considered a big enough threat he could have blockbuster feuds against other WWE powerhouses.
From there he could either be a mainstay at RAW or become the Strowman of SmackDown. It would enhance the abilities of The Lone Wolf and make him a Superstar all of us expects him to be.