Terminator 2, Magical Girl Lyrical Nanoha A's, Sly 2 (I cannot say how much I loved that game), The Empire Strikes Back, Super Mario World, A Link to the Past, Half Life 2, Mega Man 2, and Super Metroid.
Edit: How could I forget Sonic 3? The art, music, and gameplay were all improved and while the plot was still thin, it still made a story and atmosphere that strangely compelled you, especially with Sonic & Knuckles added on.
Also, Sonic Adventure 2 is better than the first one, and while Shadow may have started the downturn with crappy characters you don't care about, he himself was one of the good additional Sonic characters. Then again, this is someone who actually likes the plot/mythos of the Sonic series, at least as far as the Adventure games go.