Baten Kaitos: Lost Wings and the Eternal Ocean. Excellent lore, fun gameplay, very cool and colorful. Card-based combat, and you could earn/create new cards by doing specific combos in battle and some cards would evolve/change in real time.
The Disciples and Heroes of Might and Magic games were also a lot of fun, but it kinda seems like they've gotten worse and worse in the last few iterations.
I spent a lot of time playing Morrowind, but I never actually did the main story as a kid cuz I could never find that damn puzzle box at the beginning. Working on that now.