For me, the final season of Star Trek - The Next Generation featured two of my favorite episodes: The Pegasus and Masks. Both were great episodes, and some other episodes I enjoyed were: Dark Page, Parallels, and First Born. I scanned the episode list on Wikipedia and found that I liked between four and six episodes in each season. As an example, although I've picked up that its not a well-liked episode of the First Season, I like Too Short As Season. Returning to the topic, I'm going to mention Doctor Who. Since it essentially becomes a new show when The Doctor regenerates, I'm going to consider each regeneration as a separate show for purposes of this thread. That said, I think The Fourth Doctor (Tom Baker) time on the show was one or two years too long. After Romana regenerated (going from Mary Tamm to Lalla Ward), the show seemed to lose something and it wasn't as good as it had been.