Any game where you can explore a realistic, vast ocean is awesome. Like The Legend of Zelda: Wind Waker or Suikoden IV.
But I think my favorite game of all time is Dragon Quest VII. I've beaten it twice, and I always spend about 300 hours per playthrough. I've never played another game quite like it, in that I really felt fully immersed—like I legitimately felt alive inside of it, as if I were personally interacting with its world. A big part of what made it so unique was that every NPC in the game always has something different to say every time you progress the story's narrative a little bit. And you could even strike up conversations with your party members in and out of battle anytime you want.
Final Fantasy IX is another top fave. And the first two Breath of Fire games had a HUGE, lasting influence on me as a kid. I still adore the characters and music from all those games.
And then there's the Chrono series. Chrono Trigger had the most epic build up & climax of any RPG I remember playing as a kid. That game really got my addrenaline going, like no other. And Chrono Cross had a great story (albeit convoluted), heart, and awesome music.