Five years ago I would have answered RVD. But having re-watched all of 1995 ECW, and currently working on '96, my opinion has changed.
RVD and the stuff he does was super exciting back in the 90's. I had never seen anything like the matches he was having with Jerry Lynn. Unfortunately by the mid 2000's, the opening match at most Ring of Honor shows were running those spots. Not to mention that RVD himself has basically been doing all of the exact same spots since 1996. So I have grown increasingly tired of the whole act.
Sabu was a guy who I always enjoyed, but going back and paying attention to more than his crazy bumps, watching the character, the psychology, and the timing of the crazy spots, I have come to enjoy him far more. Sure he fucked up a ton of spots, but when your going balls to the wall doing crazy shit, that tends to happen. Also for a guy who is supposed to be crazy and could probably just shrug off any selling he needed to do, his selling is worlds better than RVD's.