#1 Bobby Roode

Ever since debuting on SmackDown Live last year after SummerSlam, Bobby Roode has had a downhill journey. He started strong being very over with the fans. He even got a US Championship reign, and defended his title at WrestleMania. But after moving to Raw in the Superstar Shake-up, he has rarely been featured on TV, and hasn't appeared on a PPV except in the Money in the Bank ladder match.
His career revival is simple. Get rid of the robe, get rid of the smile, give him a suit and a heel turn. We saw in NXT how great he was as a heel. He was turned face upon reaching the main roster, without any logical explanation.
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The crowd didn't exactly connect to the character, as he went from a smooth talking aristocratic heel, to crowd pandering babyface within 3 days. Even in his TNA days, Roode did his best work as a heel. His only run with the TNA World Heavyweight Championship came when he turned heel on his Beer Money partner James Storm.
Given that Raw has a severe lack of main event level heels, Roode's turn can also help the brand in the long term. For now, Braun Strowman, Dolph Ziggler, and Drew McIntyre are the only 3 noticeable heels on the roster.
That is, if one considers Braun Strowman a heel. Roode has the look, the in ring ability, and the charisma to make it as a main event level superstar. All he needs is a proper character, and that can be achieved easily if WWE books his turn properly.