That's why I think FFIX is better in every way. It's a lot prettier, the character models are superior (not to mention the characters themselves are more engaging, and more fleshed out). The slowdown during battles is also greatly toned down. There's also the matter of the story, which is shockingly dark despite its arguably less mature aesthetic.
FFVII may have introduced many people to the RPG genre (which is a very good thing, don't get me wrong), and I can see exactly why people rate it so highly. I think my problem with it is just that I missed the boat; by the time I played it, I'd already played FFIX, Tales of Symphonia, Persona 4 and a ton of other amazing JRPGs. I can't appreciate it like other people can in that regard.
*flails incoherently*
You know, I get a lot of hate for my love of FFIX. It's my absolute favorite in the series, hands down (though VII is only a hair behind). Zidane is my favorite hero in the whole series. I LOVE the aesthetic of IX. It's a really beautiful game. The characters are memorable and lovable, and while the story kinda took a turn into left field there at the end (the only place where it falls shorter than VII, IMO), it was still a very good plot which, as you said, was remarkably mature for the aesthetic and general tone of the game.
By the time I played IX, I had already played through I, II, the Japanese version of the actual III, tried to get through IV, just barely made it through V, adored VI, of course I'd started with VII, VIII lost me, and then I played IX. I loved all the little references to the earlier games. I loved that they kept what had worked in the past and expanded on it, rather than trying for something totally new. I loved the characters. I loved the cities. I loved the combat. I loved it all.
I'm sorry, I just had to fangirl squee there a bit. IX is such an underrated game in the series, and I think it deserves a lot more love than it gets. It is my humble opinion that it's (by far) the best game in the franchise. And while VII will always be my second favorite, I agree that it's more because of nostalgia than because it's actually that good of a game (at least gameplay wise. I will defend the story to my grave.)
And you know, I honestly missed the boat on IV, so I can totally understand your feelings with VII. Sometimes you just had to be there.