The lack of respect for Bruno is pretty surprising.
Held the WWF Title for seven years when it truly meant you were THE MAN, and sold out MSG, Baltimore, Philly, Washington, Pittsburgh, etc etc over and over and over for the entire run. Only lost the title to Ivan Koloff because he wanted time off, then had another multi year run when he decided to come back. Nobody - NOBODY - sustained his level of popularity and success for even half as long.
I think The Rock's run is a bit overrated. Let's be honest, while a star for sure, he coat tailed Austin and was always the clear #2. Plus his run was short. Being upstaged by master worker Hogan at WM hurts too.
Andre is really in the same boat as Undertaker. Outside of WM3 he was more of a gimmick guy and never a true top guy. He spent a lot of his time in other territories, too. Undertaker is just as iconic at this point.