#3 Elias

Elias debuted on the Raw after WrestleMania in 2017. While his act didn't catch on in NXT, it really caught steam once he started performing in the ring on episodes of Raw.
The simple gimmick of insulting the city WWE was in is a time-tested heat magnet, and singing about his disdain for that town only turned up the heat from the fans.
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Since he was given some freedom with his songs/promos, he was able to connect with the fans so much to the point where he often received one of the loudest reactions from the crowd on a nightly basis.
WWE might have experimented with Elias as a face when Roman reigns' departure forced WWE to switch up the alignments of some stars.
One star was Elias, as he was turned to a face who started to rag on Baron Corbin. The crowd still cheered loudly for him, only this time in agreement with the Drifter.
But WWE decided not to capitalize on his popularity either time as he failed to capture the Intercontinental Championship while Seth Rollins, Dolph Ziggler, and Bobby Lashley have held the title.
He's only been on WWE proper for a little under two years, so he still has a chance to be a singles' champion. He's already a singles' star but perhaps creative feels he's over enough without a title.