#1 Finn Balor
Let's admit it. Finn Balor isn't the same person he was when he had debuted on the main roster. An injury abruptly halted his Championship run, and he failed to find his footing since then.
If it wasn't for his match with AJ Styles, he might have plummeted his status far away from the Universal title. However, his subsequent bookings didn't help him. It only confused the fans more and subverted his status as a "true babyface" after Seth Rollins and Braun Strowman in the red brand.
So how long will he don the role? Not long enough. He should win the Money in the Bank ladder match, cash it on the champion, and become the new WWE Universal Champion. Telling that the WWE Championship is his necessity would be an understatement. It is his sine qua non.