#4 AJ Styles
AJ Styles has been a member of the SmackDown Live roster ever since WWE decided to bring back the brand split in 2016, and he's faced every opponent imaginable on the blue brand since then.
Cody Rhodes' uncle is a WWE Hall of Famer. More details HERE.
While he has had a singles match with Randy Orton before, it was a forgettable match on a random episode of SmackDown, so his current feud with the "Viper" is something new. However, it's pretty much the only new thing left for "The Phenomenal One" on the blue brand, and after its conclusion, which will presumably be at WrestleMania 35, WWE could, and honestly should give Styles a new home.
If AJ Styles does move over to Raw, then WWE better make sure to send some incredible talent over to SmackDown Live in an attempt to fill the hole that the former WWE Champion will leave if he's shipped over to the red brand.