#3 Finn Balor/Kevin Owens:

Finn Balor made his main roster debut in the summer of 2016. He received a huge push as soon as he arrived on Raw. On his first night, he beat Roman Reigns clean and in his first main roster PPV match, he defeated Seth Rollins to become the inaugural Universal Champion. Unfortunately, Balor suffered an injury during his match against Seth Rollins and had to relinquish the title following night on Raw.
If Finn Balor hadn't gotten injured, he was supposed to have some interesting feuds and matches post-Summerslam. According to Dave Meltzer, the original plans for the Universal Champion Finn Balor involved him defending his title against Kevin Owens at Clash of Champions 2016. That match would have led to a triple threat match (probably a Hell in a Cell match) at Hell in a Cell between Balor, Jericho, and Owens. The Balor/Owens & Jericho feud had the potential to be a highly entertaining feud and there's no doubt that the matches between them would have been excellent.
Instead, we got a feud between Rollins & Reigns and Owens & Jericho. The major takeaway was that WWE lost hope in Balor after his injury and didn't push him after he made his return.
Becky Lynch has been challenged HERE.