You know what I've always loved about Final Fantasy- EVERY Final Fantasy? They aren't interconnected. So you don't have to love the series at all- you can hate part of it or damn near all of it, it won't hurt your enjoyment of the ones you like becuase no game truly affects another. Hell, considering the success of Octopath Traveler, maybe they will go full on old-school turn-based fantasy realm for 16- there's nothing officially stopping them, after all!
Anyway, of what I've played:
Final Fantasy- it's an 8 bit RPG. A good one, fun monsters & well balanced and all, but primitive as all get-out these days.
Final Fantasy 3- haven't finished it, and don't really remember it. *shrugs*
Final Fantasy 4: SPOONY BARD! Also didn't finish it, my brother sold his super nintendo before I was done.
Final Fantasy 7: My first fully played game in the series, one of my first playstation games, I was blown away by the sheer scope of this game. I genuinely don't know if I'd play it again today though- I never really latched on to the characters or the story, most of my current admiration is borne of nostalgia.
Final Fantasy 8- Yeah, the story here wasn't great... but dammit, I really loved the characters in this one! I played the ever-lovin' crap out of this, right up to farming on the heaven/hell islands to try and max my stats. Easily the most time I've put on one save file in the series.
Final Fantasy 9- Not a fan, but not the game's fault. When I played this, I was the last one in amongst my friend group, so every day was a bombardment of 'where are you? No, you have to get to here so we can talk about it! I don't care if you want to grind for items/levels, I need to talk about the thing that happens!'. Getting screamed at constantly to either speed-run or have every major plot point spoiled sours one experience quite a bit. I actually deleted my save file, hoping it would encourage me to try again & play at my own pace, but no- the game just makes me mad now. *sigh*
Final Fantasy 10- One of my favorites. Great cast, great story- one of the friends above dumped a major spoiler on me & kinda ruined the endgame, but at least I was close enough to the reveal to not be completely put off. Also, one of the weirdest final bosses ever- simultaneously annoying & creative.
Final Fantasy X-2- Meh. Barbie's Adventures in Spira. Honestly just felt weird- I don't remember if I finished this or not...
Final Fantasy 12- My Absolute Favorite, hands down! I love the entire cast, I love the setting, I love the more intimate scope of the story, I just love all of it. It's not without its flaws- the first time I tried explaining Basch's background to someone I had a full mental stop when I realized I'd just unironically said 'it was his evil twin'. But I give the game credit for being so subtle about it I didn't notice in-game. I also did enjoy the gambit system- it was nice to lazily grind & just enjoy the animations instead of focusing in on stats & moves & timing. Happily re-played the Zodiac Age re-release on PS4, and honestly considering buying it again for the Switch.
Final Fantasy 13- Meh. The characters are ok, the story is actually pretty good, and I didn't mind the corridors... I did mind not getting full control of my party till a good 20 hours in, and good LORD the endgame was long! I think after 12 though, Id've been dissapointed by pretty much anything.
What do I want from the series in the future? Beats me- I suppose a good story, and some form of novelty. I like it when games do something I haven't seen before. But like I said, the nice thing about Final Fantasy is they all get to be so different- it's always fun to see what they try next!