The death of Mary Tyler Moore master writer David Lloyd, and the announcement that the sixth season (with "Chuckles Bites The Dust") will be released on DVD, got me to wondering which season of the show is the best.
This isn't an easy question to answer. Some shows have one season where everything comes together, that combine the best qualities of the early and later seasons, and where a large number of the famous episodes and moments occur. For MTM's sister show The Bob Newhart Show, for example, things really clicked in the fourth season and most of the best episodes are from that season. But Mary Tyler Moore, as I've said before, had kind of an unusual creative trajectory for a long-running TV show: instead of starting strong and then improving steadily, it had a lot of ups and downs. It started with a great first episode, then a lot of the first season was much weaker (but not all; the episode "The Snow Must Go On" is terrific). And the show's second season, instead of being a clear improvement, was sort of a transitional thing: the characters got more interesting, but there are probably fewer memorable episodes in season 2 than any other season of the show.
Then the show made a huge leap forward in season 3, with the arrival of Ed. Weinberger as producer (and, perhaps, with Jim Brooks getting more involved again; he didn't have any writing credits in season 2, while he returned to co-write the season 3 premiere -- which established the new, sharper writing style). Whereas season 2 hadn't produced many memorable episodes, season 3 produced a bunch.
Then season 4 brought in David Lloyd as a staff writer and Sue Ann as a character. Season 5 was the first season without Rhoda, marked another advance in the incisiveness of the writing (because Lloyd and/or Weinberger and Stan Daniels were writing nearly every episode), but perhaps didn't have quite as many big episodes as the following season, season 6. And season 7 showed some signs of tiredness (a clip show, a fantasy show), but, again, produced a large number of standout episodes, though maybe not one episode as big as "Chuckles."
So every season except the first two really has its own distinctive claim to be the best season; depending on which dynamic is your favorite (the home/work combination of the early seasons vs. the pure workplace comedy of the later seasons), or which season has the most episodes you love.
I think, even though David Lloyd and Sue Ann hadn't come on the scene yet, I lean toward season 3 as my favorite. I don't know I'd call it the best, but the writing is such a big improvement on the previous season that it's almost like watching a different show, and yet it still has enough elements of the first two seasons; it's almost like the second season done right. Clothing-wise, the characters have shed the terrible fashions of the first season without quite succumbing to all the terrible fashions of the later seasons. (It's a sign of the weirdness of the mid-'70s that Mary Tyler Moore, a performer famous for her legs, would find it fashionable to wear hideous bell-bottomed pants.) And it's got maybe my favorite episode, "Lou's Place." Again, I don't say this is the best episode, and my love for it is sort of nostalgic -- it was the first episode that, in reruns, really made me laugh uncontrollably. But it is kind of a perfect episode with a very typical ending: for a feel-good show, it's amazing how many episodes end in total disaster. (Something that Taxi and Cheers and Frasier and many other members of the Mary Tyler Moore "family" of shows would pick up.) So I'll go for that as my favorite, though purely in terms of strong writing, season 6 is probably the best.