#1 - Seth Rollins

Rollins has shown recently he is ready to headline any main event. However, the top of the Raw card is very crowded and it looks like it will stay like that for a while. Roman Reigns and Braun Strowman have been set up as more dominant than Rollins and programs with either aren't particularly enticing at this stage of their careers. We've seen him take on most of what Raw has to offer whereas the potential match options on Smackdown Live are incredibly enticing. Rollins vs. Styles, Rollins vs. Nakamura and Rollins vs. Owens would all be incredible and could carry the brand for months. Rollins deserves to be a top guy, and adding him to Smackdown Live would make the brand unmissable.
Paul Heyman's downfall need to be studied - Check!