Not many keep their character ever lasting, or time returns or revamps in character correctly. I think an underdog in consideration is Matt Hardy. He gets wrestling. From Version 1 to ECW Heel Champion to Broken/Woken. He stayed relevant, just as Chris Jericho is doing in NJPW. Will throw Ric Flair amongst those two, but I think its hard to argue that fact. Matt Hardy and Jericho have over took Flair in terms of longevity, but I believe as of right now, Hardy has overtaken Jericho.