Final Fantasy VII was no doubt the biggest in the series. Here you had a game in the center of the Square-Nintendo-Sony controversy, drowning in hype and soon to introduce millions to RPGs and introduce even more to what "RPG" stood for! Something like that is bound to affect the public, there's no doubt about it.
Helped by the fact that this was the first FF many people would play and that the series' stories were not interconnected, FFVII ended up creating its own fanbase, a phenomenon easy to predict in Japan but virtually unheard of in America. Sites were being written, wallscrolls were being hung, costumes were being made and pornographic fanart was pouring in like a mudslide.
As the fans were multiplying, people started researching the history of Final Fantasy, trying out the previous six games and eventually forming fanbases out of those. Who was the best leading man or love interest? Which had the best music? Actually it doesn't really matter because you're all wrong and I'm right because I've been playing since FF1 and my dad is Ted Woolsey and hsadglbji3wqeui basmndsgq
Once VIII was out, Final Fantasy was a household name, but VII kept on and still stands as one of the more recognizable FFs. Not such a bad end.