#1. Being in Seth Rollins' corner against Brock Lesnar
This option has the most meaning for Roman Reigns, as well as the entire story as a whole. Seth Rollins will challenge Brock Lesnar for the Universal Championship at WrestleMania, something Reigns did last year. That was his second 'Mania main event against Lesnar, with the first one coming at WrestleMania 31.
The two were having a brutal slobber knocker of a brawl before Rollins came running down the ramp to cash in his Money in the Bank contract mid-match. He would walk away with the Beast's title, something he could do again in less than six weeks' time.
But this time, he could have the support of his brother during the match. This also ties in with the fact that Reigns had beaten Lesnar for the big red belt at SummerSlam, before being forced to relinquish it due to his leukemia returning.
After Rollins dethrones the Beast once and for all, we could get a huge celebration with all three members of the Shield, especially after they seem to be reuniting again. It would be an extremely emotional moment, possibly the last one with Reigns, Rollins, and Ambrose for a good while. It probably is the best possible sendoff for Ambrose, to spend the moment with his two brothers, one who conquered the Beast and the other who conquered leukemia, again.