#4 Madison Rayne
Madison Rayne is one of the few standout women's wrestlers from TNA who is still under contract to the company. She debuted as just another member of the roster in 2009 before joining The Beautiful People and later coming into her own as a fantastic heel.
In her seven years with the promotion, she has held the Knockouts Championship a whopping five times and has done battle with virtually everyone who has come through TNA. That said, she has fallen to the wayside in recent years and would benefit from a change in scenery.
Of course, it might be a while until she is WWE bound depending on when her TNA contract expires, but she would a great pick-up by NXT, nevertheless. She could receive an all-new character, though, given her success in TNA, it might be better for WWE to allow her to keep the Madison Rayne name.