Edge is just an interesting character. He went from a guy who ran through the crowd and didn't speak and was over, to being in a tag team who was over mostly for their mic work. He's really versatile. He can get a good match out of Cena, he held his own in the ring against Guerrero or Angle or Benoit, then he can take the hardcore bumps in all the matches with the Hardys.
Just looking at the list Larry put up, post-surgery, and it couldn't be more all over the place. Rey, RVD, Cena, Taker, Orton. It doesn't matter if they work a slow plodding style, a high-flying style, they're mat-based like Benoit or Angle, or a hardcore style like Foley. You can drop him in with anybody, and he can work that style and make the match entertaining if not great. He's not the Albert Pujols, one of the greatest ever types. But he's very Craig Biggio. There's something to be said for being above average at everything and doing the small things. Constantly very good, rarely great.