#1 Roman Reigns vs Bobby Lashley vs Brock Lesnar (Universal Championship)

Bobby Lashley pinned Roman Reigns clean at Extreme Rules in a match he had to win to remain as a top-level main event superstar. He should ideally be given a Universal Championship against Brock Lesnar at Summerslam. But Roman Reigns will continue to whine about how he is the "uncrowned" Universal Champion. There has to be an ending to this feud. This would provide that and the inclusion of Lashley would likely keep interest levels above zero. It would also provide a different style to the WWE Championship triple threat match.
The match would likely be an aggressive, smashmouth style brawl reminiscent of last year's main event of Summerslam. The most probable scenario would be Roman Reigns finally conquering it all and winning the Universal Championship, but Lesnar's reign has been too tyrannical and long to blemish the moment he loses the title. Honestly, if Reigns wins, the entire part-timer story would have been a waste of time as he is just not going to get cheered. Bobby Lashley could be the one to end the Beast, but we have a more popular choice waiting in the wings.
Brock Lesnar shockingly retains the Universal Championship but suddenly, Braun Strowman's music hits and he runs down the ring. He takes out the groggy champion and cashes in his contract. We get a short and competitive match between the two, which ends with Strowman hitting multiple Powerslams and pinning Lesnar clean in the middle of the ring. I would have originally had Seth Rollins win the Universal Championship but since Strowman won the Money in the Bank ladder match, he could easily replace Rollins in terms of popularity.
Brock Lesnar's reign of terror must end at the hands of a popular babyface who will be cheered while he does it otherwise this entire reign has been a waste of everybody's time. Even if Roman Reigns wins and immediately loses to Strowman, the moment of Brock losing the title would be ruined by a negative reaction.