I didn't really care for the Simpsons.
The main thing is, I only watch shows with an actual story, so trying to maintain one for over 100 episodes is really hard, since at that point, it's usually just delaying things for the sake of getting more episodes and in turn, more money. Sitcoms might be fine for hundreds of episodes, but action shows always drag and always go downhill, because you can only milk a story for so long.