I still have to finish FF8 some day. I started it and kind of liked it, but never got into it. Maybe now some of the fan made HD graphics mods for the remaster are finished.
FF6 is peak, though. I have an emulator on my phone with the Woolsey-uncensored romhack version. Love that game.
From a design perspective, I think you could safely pick anything from V to XII and say it's the best one, honestly. VI and Chrono Trigger really stand out as the most refined in terms of game design and systems from that particular era.
Without spoiling anything, the episodic storytelling style is taken to its limit in the game's "part II", and it allows for some really clever writing. VI is one of those games that kept me thinking long after I finished it.