I was once a pretty big fan of this series, but I'm more cautious these days. FFXVI really let me down, and while FFXII, FFXIII and FFXV were all enjoyable enjoyable games to me, I do feel like each lacked something I'd come to expect from an FF.
I've played (and completed) I, IV, VII, VIII, IX, X, XIII, and XV.
In addition to those, I've played large chunks of VI and XII, but just never got around to completing either.
Most recently, I bought the pixel remaster of the first game on Switch, and completed that. I loved it. Sometime next year, I'm planning to play FFII. And then I have III, V, and VI to look forward. So, even if SE never make a good FF again, there's plenty left to explore.
Also, you can still count on Square to make a good RPG, if not a good FF. I played Octopath Traveller II this year, and loved it. In addition, they remade both Star Ocean 2 and Mario RPG, which I played recently. Finally, there are the Dragon Quest games (I played both I and XI this year - and loved them both). Guess I'm a bit of a JRPG nerd.