Should stay in NXT: Lars Sullivan
The Freak of Nature has carved out a niche in NXT as the dominant 'big man' of the brand, and that's where he should stay. While NXT is the home of great technical wrestling, there's always something special about seeing a big man in the ring.
Recently he proved his dominance over fellow gigantic man Killian Dain. Longtime NXT fans knew that when Sullivan was victorious, it likely meant that Dain's days in the organization were numbered, and that was certainly born out when Killian was called up to the main roster along with his Sanity mates Eric Young and Alexander "the Ax Murderer" Wolfe.
Sullivan has a great look, and his mike skills are pretty sharp, but he is a bit stiff and awkward in the ring. He needs more experience between the ropes before he is ready for the main roster, and he can gain that right where he is on NXT.