#3 Kevin Owens

(I know, I'm ignoring the roster split. Finn is on RAW, and Kevin is on Smackdown Live.)
SD Live! is hurting its star power. Instant fix: send the leader of the Balor Club over to shake things up for team blue. As Finn is setting goals for himself and pandering to the crowd, down comes KO to interrupt.
Cody Rhodes' uncle is a WWE Hall of Famer. More details HERE.
Kevin Owens doesn't seem like the type of guy to like taking a back seat to anyone, and that could certainly be the case if Finn Balor decides to jump ship to the blue brand. Throw in the violent version of KO, angry because someone is stealing the spotlight, and there you'd have the premise. It would win all the Slammy awards (if they still existed).
It wouldn't have to be for a title because these men have so much star power in their own right, a title wouldn't be necessary. For that matter, the Demon King avatar of Finn Balor wouldn't be needed either as it would be about skill and the rise of Balor.
The best part about this matchup is the possibilities of in-ring performances and a match of the year candidate. Both men are immensely talented and it'd be a gift to the WWE Universe to see them working hard for a shared goal: the WWE Championship.