Mine has to be Dragon Quest: Rocket Slime, a DS spin off of the Dragon Quest series that sees you playing as a slime operating a tank and rescuing the people from your town. You run around the overworld, collecting items to use as ammunition and saving money to upgrade your tank. The art and music are just as great as you’d expect from the Dragon Quest series. It made fantastic use of the DS’s dual screens. It’s also written for a younger audience, so a lot of it is just really silly and fun! Try it out for sure, I’m so sad there’s no sequel :(
Terranigma - Came out at the end of the SNES era, and was never released in the US. Gameplay wise it’s kind of similar to 2D Zelda but with RPG level mechanics, spells, and jump/attacks. Where it really shines is the story though. In that area I think it holds its own against the giants of JRPGs from that era like FFVI and Chrono Trigger.