The best season of "The Mary Tyler Moore Show," season 4, gets DVD-ified on June 20.
The show improved massively in its third season, probably due to the arrival of writer Ed. Weinberger as a producer: all the comedy writing got sharper and several characters suddenly went from caricatures to three-dimensional comic creations (especially Ted and Lou). The fourth season continued the improvement and added Sue Ann (Betty White) to give it an extra edge. Famous episodes include "The Lars Affair" (Phyllis thinks her never-seen husband Lars is having an affair with Sue Ann) and the episode where Lou's wife leaves him, an episode Jay Sandrich was reluctant to direct because he felt the audience would hate her guts for leaving such a beloved character.
This was the season that brought David Lloyd to the writing staff; it was his first sitcom gig, but he instantly got the hang of it and became one of the most prolific writers in television history. His specialty was writing scripts for high-toned ensemble shows in the MTM mode, like "Taxi" -- for which he wrote the episode where Elaine likes a guy who likes Tony, and the episode where Reverend Jim adopts a dying racehorse -- "Cheers," "Cheers in an Airport" (aka "Wings") and "Frasier." His most famous script is unquestionably the one he wrote for the sixth-season MTM episode "Chuckles Bites the Dust." Oddly enough, nearly all his best work was for shows which he didn't have a hand in creating or developing.