#4 Finn Balor
Ok, this might be a bit tough to happen considering both are on different brands, but with Finn Balor just wasting away on RAW, it could make sense to move him to Smackdown.
He's fit, one of the best workers in WWE, is liked by one and everyone, and has huge star power. Balor ticks all the boxes and more.
Moving him to Smackdown could also mark the return of the Demon King, a gimmick that is loved by everyone but has been shockingly shelved for reasons unknown.
Balor and Bryan could turn into an exciting rivalry with the former as Demon King taking Daniel Bryan with all his intensity. In equal measure, the former Universal champion could end up reuniting with the "Good Brothers" to reform the "Balor Club" which can keep Bryan's shenanigans in check and the feud a bit edgier.