#2 Nick Aldis
In professional wrestling, there are very few who can claim high-level of success without having worked for WWE. For years it was accepted that WWE was the place to go for the greatest of success.
However, names like; Sting and Kenny Omega would prove everyone wrong. Agreed these names worked for WWE, it should be noted for a limited period, in comparison to their extensive careers.
Nick Aldis is a wrestler who fits the mold set out by Sting and Omega. He has yet worked for WWE. Strangely enough, Aldis is married to current WWE wrestler, Mickie James, but has yet debuted for WWE. Instead, he has chosen to work on the independent circuit, where he is the current NWA World Heavyweight Champion.
What makes Aldis successful is his character portrayal and extensive ring credentials. During his time in TNA (now Impact Wrestling) Aldis was successful in tag team and singles wrestling.
Whereas, working with the NWA he has had excellent matches with Cody Rhodes. Regardless of his position at present, he certainly could benefit from joining WWE. Moreover, he would help improve the NXT UK brand.