#4 Rusev
Rusev was a stand out from the early days of NXT. He was a big man, with a distinctive look and personality. He understandably advanced to the main roster with a lot of momentum behind him, booked as a dominant heel en route to a WrestleMania debut opposite John Cena.
Despite his talent and unique presentation, Rusev largely fizzled afterward. Besides a few pushes at the US Championship level and a feud with Roman Reigns, he has generally been planted in the middle of the pack. Though his Rusev Day gimmick demonstrated an uncanny ability to connect with the crowd, if anything, The Bulgarian Brute saw his stock sink in the months to follow.
A fresh start in NXT could be the best thing for Rusev. His size and star power could make him an instant upper card threat. More over, his understanding of how to connect with the hardcore fan base could be best served in appealing to the NXT audience.