#4 John Morrison
The man with the most ring-names in the business, John Hennigan fka John Morrison in WWE has had a pretty successful career ever since leaving the company in 2012. Morrison has been a major star in both the US and Mexico. He was a top star in AAA winning multiple champions in the promotion under the name ' Johnny Mundo'.
The Guru of Greatness also appeared in Lucha Underground where is a former Lucha Underground Champion.
Following his stint in Mexico and American indies, Morission would sign with IMPACT in 2017. He defeated Austin Aries at Bound for Glory 2018 to win the IMPACT World Championship. He would hold onto the title for seven months before dropping it to Brian Cage at IMPACT's Rebellion pay-per-view in April. Morisson left the promotion following his loss to Rich Swann at Slammiversary. Morrison hasn't ruled out a return to WWE and has always been complimentary towards Vince McMahon & Co.
Morrison would be a valuable addition to the current NXT roster. Much like Drew McIntyre before him, Morrison was once touted to be a big star in the company. While he ends up winning numerous titles during his first stint with the company, he has become a main event star since leaving the company. He could also be a mentor to the young, upcoming talent on NXT with his experience of working Live TV.