Final Fantasy 1 is groggy as all fuck. I lurve it. Never beat it.
Final Fantasy 2 has some of the best music in the early part of the series, and a really interesting hook. The mechanics are exploitable, but they're exploitable in a fun way. I lurve it. Never beat it.
I don't like Final Fantasy 3 much.
Final Fantasy 4 is a phenomenal emotional journey for me. It's probably the FF game that I've beaten the most. 4 or 5 times. Story is top-notch. Gameplay is lackluster.
Final Fantasy 5 never really clicked for me. I dunno.
Final Fantasy 6 is probably my favorite game in the series if I'm forced to pick. Story and gameplay were both at their peak here.
Final Fantasy 7 was my first FF. It was my first grownup RPG. My first non-nintendo video game. I love it. I will always love it. It's not that good of a game.
Final Fantasy Tactics is SO FUCKING GOOD. One of my favorite games ever. I never beat it, but only because of that weird fight at the end that you can only win if your main character is a high level chemist. That was bullshit.
Final Fantasy 8 is a really really good game and people who hate it are dumb.
Final Fantasy 9 never really clicked for me. I might have been too old when I played it the first time. I'd like to give it another go someday.
Final Fantasy 10 has a decent story, but hits a series lowpoint for presentation. The mechanics, however, are the best in the series. So all around I'd say it's a great game. One of my favorites in the series.
Then the Final Fantasy series ended and there were no more games.