I would say Final Fantasy, but that IP has gone full circle in a lot of ways.
Which era of FF do you think was mediocre/bad and which one became good?
I find 4,6,7,8,9, and to an extent...10 far superior to 1,2,3 and 5.
I say it went full circle though because of 13 trilogy, and while I enjoyed 15 and FFVIIR, they are not on the level of the golden era IMO. Never played 12, can't speak for it.
I loved 14 though, great MMO and it had that classic Final Fantasy feel to it. The only reason I stopped playing is because MMOs are bad for me IRL, so I swore off them.