In light of my previous post on the Simpsons, I thought I would give a breakdown of what I think about the changes the show has undergone over the previous twenty years.
Prehistoric Age: 1987-1989: This era covers the shorts that aired on the Tracey Ulman Show. These shorts, while charming and funny in their own crude way give little indication of the brilliant sitcom that was to come. It is during these years that the character designs of the Simpson undergo the most evolution; going from characters that could be mistaken as crude ripoffs of the Simpsons, to the familiar forms that appeared in Simpson's Roasting On an Open Fire.
Golden Age: Christmas Special Through Season Two: The beginning of classic Simpsons, these first three seasons saw the show rise to meteoric popularity that it would never enjoy again. There was also considerable evolution during these three seasons. At the beginning The Simpsons had more in common with the down to earth King of the Hill than more surreal cartoons like South Park and Family Guy. The shows produced during this era are funny and a definite improvement over the shorts, but they are not quite The Simpsons most people know and love.
Silver Age: Season Three Through Season Six: Season three was where the show developed the style it is known for; biting satire, an irreverent attitude towards just about everything and a constant stream of good jokes( and I mean jokes, not just Homer getting hit in the head or Family Guy style pop culture homages with no actual joke). The show also got progressively wackier and more cartoonish during this era, but this worked as long as the show never strained from the formula listed above. Most of the episodes that you would find on any list of the best episodes of The Simpsons would be from these seasons.
Bronze Age: Season Seven Through Nine: These three seasons mark the end of classic Simpsons. Season seven, though still very entertaining, feels creatively exhausted compared to the previous season. This continues through season nine with a marked decline in the quality of episodes. During these seasons the show continues its trend of becoming more wacky, but without the satire and jokes to make it work. Starting around season 8 a very noticeable trend emerges of episodes opening strong, only for the plot to move in a weird direction and end on an unsatisfying note. There are still some best of list episodes scattered through these seasons, but they are comparatively scarce during the bronze age.
Dark Age: Season Ten to the Present: The Dark Age is the age of what the fine folks over at Dead Homers Society refer to as "Zombie Simpsons". The term is appropriate as by this point the show is only The Simpsons in the most superficial sense. Few if any of these episodes meet the quality of average episodes from pre-bronze age simpsons and in general you will few episodes from these seasons on best of lists. The show continues to evolve, but not in the sense that it becomes better. Today The Simpsons feels like a neutered imitation of the original. The characters look like The Simpsons, but they lack the qualities that made them famous in the first place.