I just wanted to point out that Crazy Bus was a Proof-of-concept for a Genesis BASIC compiler and never released commercially and Captain Novalin wasn't really meant to be a widespread game, it was just for teaching kids about diabetes.And there ARE terrible games today. I mean sure, there's nothing actually unplayable like there was in the NES days (looking at you, Action 52), but you can't say every piece of shovelware released to the Wii and DS and every tie-in to a movie was mediocre, much less good.
It doesn't just matter how much work goes into a game, or how nice it looks. If it's boring, broken or enragingly hard, it has failed at the point of a game. Which is something that you'd actually WANT to play. (Opinions differ depending on the game of course)
On the actual topic, I'd say Sonic Heroes really. It's mostly my fault for building it up for myself and I really loved Sonic Adventure 2. I haven't really had many other games that have disappointed me otherwise much.