Dated: Mobile Suit Gundam - Journey to Jaburo.
The controls are wonky compared to newer games, but the overall tone and feel of the missions and how the Gundam handles once you master the controls made me feel like it was one of the best Gundam games. Every other game I played felt a bit too arcadey, didn't have the sense of urgency to the battles like Jaburo did. I liked how desperate it was, it actually translated the series it was based off of well into game format. Would love to see another Gundam game like it, with more accurate but overall similar controls.
Dated: Quest for Glory series. To me this was the best overall Sierra adventure series. Over 5 games it maintained a story arc, even while the last game was a severe departure from the previous entries mechanically. The writing was especially well crafted, the paths you could take between each class were interesting. Although the story was fairly linear you could miss or just ignore plot threads and still complete the game, which would affect the ending. I can't rightly recall if after you save the game at the end and import it to the next, whether the endings you get in all the previous entries had impact on the final game but I felt like my choices mattered at least in each chapter. I know other games have tried to do this and met with limited success, but I'd love to see QFG redone as a modern RPG arc. Let your class decide some of the game events, how they occur or even if they occur, let your decisions actually impact the ending signficantly (rather than moral choice, it either lessens your impact as a hero or strengthens depending). And most of all I want another game with that style of humor, blended with the myths of many cultures spread across a wide land of interesting and awesome places. One note, its the only RPG-ish game where I've found that rolling a thief meant you actually did some work as a thief and not just become a faster, weaker, lighter-armored fighter or archer.