#4 Braun Strowman
This is the most logical option. This week, when the Universal Championship match was changed to a one-on-one match, Strowman interrupted in Paul Heyman’s promo and behaved as a face. He has lately been behaving as one in Live Events and his issues with Drew McIntyre, a pure heel, seem to solidify him as a face.
Prior to turning heel prior to Hell in a Cell 2018, Strowman was one of the most over baby faces of the company, taking part in several shows and events of other countries to promote the WWE. He had been the top baby face of the company which fans had liked, so bringing him back as a face will certainly do wonders for the television ratings.
Him winning against Brock Lesnar at Crown Jewel (now, where is that event going to take place?) and entering into his first Universal championship reign will surely delight the fans. He can prove to be a dominant champion and can make the red belt prestigious.
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In real life too, Strowman is a person similar to Roman Reigns and John Cena. He can certainly carry WWE on his back for some years, before the next face is chosen or till Roman Reigns makes his return.