I can't just name one. I'd have to go with naming a top three.
1. Lufia: Curse of the Sinistrals
Excellent re-imagining of one of my favorite games. I've always liked real time battle systems over turn based. The localization and voicing and even the rewritten story were all full of love - just like the original. That's something I find extremely rare these days.
2. Breath of Fire V: Dragon Quarter
An intense story that I really got into. For as much anxiety as I felt when hearing about this game, it sure kicks ass. An intriguing battle system that had me screaming and cursing in both fear, surprise and anger, and when I do that you know I love a game. :p It's definitely my favorite of the series by far.
3. Final Fantasy XII
I really felt like I could get into this world. For example, I could insert myself into the team and the story would welcome me. There were a multitude of things to do, but not completely sandbox like Romancing SaGa. Deep, detailed lore and beautiful, scenic locations. FFXII's Ivalice is definitely the one video game world I would love to live in.
...Buuut, since the question was only for a single choice... FFXII. It's the only game that has kept me thinking of it outside the game itself.