Garfield: Caught in the Act on Sega Genesis has maybe the most impressive animation I've seen on a 16-bit system. Better than a most later 2D games, even. The Game Gear version is pretty good, too, for Game Gear.
Rugrats: The Search for Reptar does a really good job at feeling very much like the show. Of course it's 3D, so it doesn't look exactly like the show, but you get to explore a lot of locations from the show, laid out in very logical fashions. From the main house, to a bunch of locations only seen in single episodes.