1. Roman Reigns vs. MJF: Acknowledge me vs. I'm simply better than you

Roman Reigns has defied the stigma that marred his character following the dissolution of the Shield in 2014. Until last year, Reigns was yet another example of WWE's idealistic view of a main event calibre star, where marketability takes precedent over ability.
Since returning at SummerSlam last year, Reign's character work has been immense, befitting someone who shares the same lineage as a name like The Rock.
Cody Rhodes' uncle is a WWE Hall of Famer. More details HERE.
Although a Reigns heel turn sat atop wrestling fans' wishlist ever since he uttered the words "sufferin succotash", absolutely no one could've predicted the metamorphosis that this generational talent would undergo.
Reigns has shown an ability to go toe-to-toe with the best on the mic and in the ring producing performances that've sown the seeds for a future transition to Hollywood, should that be of interest to the Head of the Table.
What tale then could we see told by an MJF feud, since all great feuds need a solid foundation? Reigns, unlike MJF, had to change the content of his character in order to be a top star. This means that there are character weaknesses that can be exposed, such as the fact that Reigns has not always remained truthful to himself.
He's either behind megastars like Cena and Hogan, or he's the grand patriarch of the Anoa'i wrestling dynasty. MJF and Reigns are in similar positions, but with enough difference between them to exploit the story.
While they both share an inflated ego, Reigns shares a passion for making sure he furthers the legacy of his bloodline with his family by his side. Whereas MJF is exploitative, seeking alliances only when he can reap the rewards and further his career.
The fact that they're so similar but still so different plays into the lucrative nature of any prospective feud between the two.