Everyone has their own opinions about games, and everyone is entitled to like any game they want. But you asked, so here it is.
I liked FFVII, but it was the begining of the end of square for me. They started to rely more on graphics and gimicks than actual storyline (even though the storyline was pretty good, the last time I've been able to say that about a final fantasy game until XII came out), and even then, it didn't really bring anything new to the genre. It had a new magic system, sure, but name one final fantasy game that has a magic system like another. Every other final fantasy before it brought something new to the gameplay or world that made the game franchise as a whole better.
The original final fantasy set up the baseline and was very true to its DnD roots (whether or not that was the inspiration for the game, but I think I remember reading that it was). Final Fantasy II set up the beginings of the interchangable class system (though it wasn't done particularly well there) and set up set characters rather than player-made ones. Final Fantasy III set up the world a bit more, introducing save points for the first time (in the original versions, at least) and introduced moogles (love 'em or hate 'em). Final Fantasy IV solidified the combat and storyline, and introduced the row function in the game. Final Fantasy V brought in the interchangable Class System that crops up from time to time (and is generally a fan-favorite). Final Fantasy VI (my personal favorite) probably introduced the most, with the inclusion of magic affecting leveling stats, the ability to change members of your party, and the inclusion of limit breaks (yeah, they were there, they were just REALLY hard to pull off). After FFVI, nothing really new was added to the games. FFVII was graphically beautiful (especially for the time) and was a huge game, but nothing new was really added to the Final Fantasy world or the gameplay of the series as a whole. It seemed to be more about the look rather than the feel. It even seemed like a step down for teh story because, well, the characters were more adult and believable in VI, and the villian was more imposing and threatening as well (because, let's face it, Sephiroth summoned Meteor and TRIED to destroy the planet. Kefka brought about the power of the espers and DID destroy the planet. Halfway through the game!)
After FFVII, everything went downhill. FFVIII was widely regarded as an attrocity (with the story being convoluted, the magic system being nearly unworkable, and the junction system being overly confusing), FFIX, while faring a little better, suffered from most of the same problems (and personally, I couldn't effing STAND the game), FFX was FFVIII as far as plot, and the system was ridiculous and completely linear (seriously, there's really not any way to truely customize the characters in any meaningful way), FFX-2 was a cash grab, plain and simple, FFXI was an interesting idea, but it didn't do that well outside Japan (I played it for a little while, and it was pretty impossible to solo quest). The last Final fantasy game I played was XII, and honestly, I rather liked it. It seemed to take Final Fantasy back to its roots, storywize anyway. The system was odd, like a cross between the sphere grid and the job-class system, but the story was adult and I actually cared about the characters. Especially Baltheir. He was a badass.
All in all, the SNES days were the heydays of Square (and Enix, back when they were seperate companies), and ever since it all became about graphics, everything's gone downhill, with a couple of 'nice try's in the interem.
