I love MM and AFM for their themes and their hilarious, campy callouts and voice acting. The music in both games is fun and well suited too. But the games themselves are pretty basic fan layouts and very similar to one another. There's room at the top for more innovation and I think GZ in particular brings that in spades. Like the other "greats" it succeeds in part through being campy both in theme and callouts. I get the complaints about the main voice actor/news caster and maybe you could argue the one place the older games easily beat GZ is in the callout department. But GZ's layout is way more interesting (though arguably fan-like to a degree in it's own way) and the rules are much, much deeper than either MM or AFM. Not denigrating those earlier games, but again I think GZ earns its place at the top and it shouldn't be supplanted there unless an even better game comes along to dethrone it.
Having said that, I can see JP eventually falling down the list as the Elwin effect wears off. That game has a great layout and amazing ruleset, but it falls flat in theme integration and callouts in particular. And I think it's those things that will let a game withstand the test of time...