Many fans debate on which is the best season of Buffy the Vampire Slayer. Seasons are ranked below based on the average quality of their episodes. The average point total for the season is in parentheses.
The high points of season three can be described as the two-part season conclusion ("Graduation Day, Parts 1 and 2") and the two episodes in which Alyson Hannigan spent much of the time dressed in tight leather ("The Wish" and "Doppelgangland"). It is also a deep season. Twelve season 3 episodes fall in the top 50 of all episodes. The low point came early in the season. The first seven episodes produced five of the six weakest episodes of the season. However, no season 3 episode made the bottom 10 of all episodes.
The popularity of season 2 appears to be largely due to the popularity of the season arc. The two-part season conclusion ("Becoming, Part 1 and 2") is the high point. Next comes three arc-heavy episodes ("Surprise," "Innocence," and "Passion"). In particular, Spike and Drusilla appear to do the most to put season 2 so high. The worst episode with Spike and Drusilla ("What's My Line? Pt. 1") is still ranked higher than the best episode without them ("When She Was Bad"). Marti Noxon and Joss Whedon wrote or co-wrote ten of the thirteen best episodes this season. They wrote or co-wrote only two of the remaining nine episodes. Many of the stand-alone episodes drag the season down. Five of the ten weakest Buffy episodes are in the second season with "Ted" not being much better.
It seems as if Season 5 would have been better if Riley had left Sunnydale earlier. Of the top-11 episodes this season, Riley appears in only two—"Fool for Love" and "Family." Riley was relegated to the B-plot in both of those episodes. On the other hand, Riley appears in eight of the 11 weakest episodes and plays a significant role in many of them. Otherwise, season 5 has no episodes in the bottom ten across all seasons and is the only season with two top-five episodes across all seasons ("The Body" and "The Gift").
Season 6 is arguably the most polarized season. It contains the best episode ever—"Once More, with Feeling"—and the worst episode ever—"Doublemeat Palace." "Bargaining, Part 1" is the second best season opener ever and "Bargaining, Part 2" is the best second episode of a season. "Once More, with Feeling" and "Tablua Rasa" are the best back-to-back episodes of Buffy. The last four episodes ("Seeing Red" through "Grave") are another high point, although "Grave" is the weakest season finale. Giles seems to help the most. He appears in six of the top-ten episodes and in only two of the remaining twelve.
The episodes to either side of "Once More, with Feeling" and "Tablua Rasa" drag the season down. The bottom-13 episodes of the season is made up of the four episodes before "Once More, with Feeling" ("After Life" through "All the Way") and nine of the ten episodes after "Tabula Rasa" (from "Smashed" through "Entropy"). The latter streak is the worst 10-episode stretch in all seven seasons of Buffy, with only "Normal Again" appearing in the top-60 episodes across all seasons. To be fair, the bottom-13 episodes in a 22-episode season include two episodes in the top half, and "Life Serial," "Dead Things," "After Life," "Smashed," and "Entropy," have average, rather than poor, rankings.
Season 4's "Primeval" is the lowest ranked episode in which a Big Bad is defeated once and for all. It does not even make the top-five for the season. "Hush" was the high point of the season. It is the top episode of all time in which none of the characters sing. The five worst episodes of the season were made up of three of the four episodes after "Hush" and the two worst episodes of the season, Tracey Forbes's "Beer Bad" and "Where the Wild Things Are."
Fans do not seem to have strong opinions about season 7 episodes. "Chosen" is the only season 7 episode in the top 15 of all Buffy episodes, but no seventh season episode falls in the bottom 15 of all episodes.
Season 1 falls in last place in part because it had only one top-20 episode. As a general rule, fans seem to like season 1 episodes written by either Joss Whedon or David Greenwalt (except for Greenwalt's "Teacher's Pet") and rate episodes written by others as being average or poor. It is probably no coincidence that Whedon and Greenwalt are the only two season 1 writers who were still around in season 3.
Fans debate over which season is the best or the worst. Seasons 4 and 6 in particular get much criticism. The big surprise is that there is very little difference between the seasons. Seasons 2 and 3 appear to be the strongest, and season 1 appears to be the weakest. However, the differences between the best and worst seasons are small. Season 7 (ranked #6) is one and one half points behind season 5 (ranked #3). Only 1.6% of the quality of an episode can be attributed to the season when it aired.
On the other hand, an additional 25.4% of the quality of an episode can be explained by whether an episode is the last or second-to-last episode of a season with the second-to-last episode being better than most previous episodes and the last episode being even better. An additional 2.1% of the quality of an episode can be explained by whether or not an episode is part of a two-part episode. Knowing whether an episode is a season opener explains a negligible amount of episode quality at this stage (0.3%). However, it is useful in explaining why season openers, which are usually written and often directed by Joss Whedon, tend to be worse than other episodes written and directed by Joss Whedon.