Just to briefly go in the opposite direction, I watched the show long after its decline and into its second decade of decline because I watched the whole FOX animated lineup for a while mainly for
King of the Hill and
American Dad (later adding
Bob's Burgers and just left it on inbetween for garbage like
Simpsons and
Family Guy. (The latter sometimes having a decent one-off episode or two.) And there's a Season Ninteen episode that I do quite like: "Eternal Moonshine of the Simpson Mind"
And it has a good number of rave reviews and not just of the usual "good for modern
Simpsons" type. Won an Emmy. Al Jean picked it as one of the five best episodes ever, also a potential series finale type:
showrunner Al Jean discusses what episodes that have previously aired might serve well as a series finale. He regards "Behind the Laughter" and "Eternal Moonshine of the Simpson Mind" as the strongest candidates
Of course, he also wrote The Movie, which was atrocious. One day I will go back and find all the people on forums who said "Spider-Pig is legitimately laugh out loud funny" and bring the reckoning to them.