Too many to choose from.

Part of me wants to say
Star Ocean 2, but then
Super Mario Rpg is what brought me into loving Rpgs in the first place.
I want to say
Final Fantasy Tactics since I have fond memories of staying up all night, drinking warm rum and playing this shyt...but then there's
Tactics ogre which is arguably the better game. I wanna say Final Fantasy 8 since I've more than 1000 hours playing that glorious games and fukking up people in the Card game....but I've prolly got 5 times that in Morrowind, not counting the game of the year edition....
.......Star Ocean 2, fukk it.

When I got Dias Flac, THAT, WAS, IT. I refused to let him go to waste like Magus did in Chrono Trigger for me 'cause I got him late and never bothered to level him up with the rest. Super Mario Rpg is a miniscule second.