5 and 6 for me. I think, with 5 (originally unreleased in America) they made the mistake of give full freedom to character occupation development, you can literally spend months having all your characters learn everything from all classes if you want. This was more or less fixated in 6, and i think all the other games.

It is, too tempting not to have your fighter/rogue be also a mage, healer, summoner, mimic or what not lol.

6 story is too good, there is in an opera in there lol. Of course the earlier ones are nice as well, tho i guess you'd need a guide for full completion.

Those years where Enix was an actual rival, also had interesting things like the Tales series the very first one Tales of Phantasia was nice, and the first two Star Ocean games.

Someday i hope to have time to play games again, or perhaps online it is, if i manage to live in a place with good connectivity unlike now.