I think Reigns does have potential if they let him develop his own personality, assuming he has one. He can also improve in ring with a few more years of working with quality guys like Rollins, Ambrose, Ziggler, Wyatt, and Bryan. I really think they should have had him defeat Barrett for the I-C title and had a run with that for a while before moving further up the card. It's like he's done very little to deserve where he is...
Some other performers I felt were underrated in-ring performers:
Kanyon & Perry Saturn
"Gorgeous" Gary Young
Rick "The Model" Martel (granted he was successful in the AWA, Japan, and Canada but he always struck me as underrated in WWF)