Roman Reigns and Charlotte. I was one of 3 people hyping her up before she got promoted. I was told she gets carried in all of her matches, has no charisma, and would end up like Natalya. Now, she's generally agreed upon to be the best and most successful NXT female callup.
"There are a lot of wrestlers who did NOT get hyped up in NXT only to do really well once they hit the main roster......"
KO and Balor are out of the running. They were hyped up to the max in NXT. Xavier Woods is a good call. Braun didn't have much hype in NXT. He got strong booking in a few matches and then moved up without much noise being made and did great. All 4 horsewomen had massive hype and they were the women's revolution so they don't count. Alexa wasn't pushed that hard but has shined on MR.