Nostalgic:
Super Mario RPG. I know that by today's standards, the combat system is a little dated (yet it is still fun even compared to other turn-based RPGs), the story is flimsy (almost even by Mario standards), and there are plenty of re-skinned enemies, but it's just so much fun. It has aged well, IMO. Hell, gameplay-wise, it beats a few modern day RPGs.
Recent:
Assassin's Creed 2. The combat still leaves much to be desired, it's not as hard as AC1, seems less focused on stealth than AC1, and the plot is borderline ridiculous (in both the good and bad ways), the later "Truth" puzzles get downright stupidly hard (and not in the good way), and there is a trick to being able to skip the first stage of the end-boss (before you fight him with your bare hands). Yet I still loved every single second of it, becuase it was fun, the story had me interested even in it's silliest moments, and there were good characters. And did I mention it was fun? That's kind of a big thing...
Also, I agree with the guy who said Skies of Arcadia.