FF -. It's good for a NES game. A nice intro to the genre but nothing particularly special.

FF2 - What were they thinking? I like the early foray into a more character driven game, but the gameplay is simply a nonstarter.

FF3 - Decent advancement over the first game, but still nothing terribly special. The start of the job system would be more notable to me of I cared for the job system. I prefer set classes like in FF4 and FF9.

FF4 - My most nostalgic entry in the series. This is where it really all began for me. I had rented and not finished FF before this, but this was the first FF I owned and it made me a fan of the series. It will always hold a special place in my heart for that reason.

FF5 - A step back from FF4 in nearly every way. The characters, villains, story, settings, and yes, even gameplay are all worse. As I've said above, I prefer FFIV's classes over the job system. It's very customizable. That's great for people who care, but I'm just not a huge fan. The graphics are a bit nicer, but that's not a big deal and visuals are still closer to FF4 than FF6.

FF6 - In contrast to FF5, this improves on FFIV in nearly everyway. I'm gonna stop for now because doing this all in one burst is too much. I have more to say in this game.