Cheating and giving two answers.
1 - Some Assembly Required - A lot of times, School Hard is mentioned as the episode where Buffy really found its feet. I always go with this because it's an early example of one where the bad guys have reasons and you're allowed to sympathise with them even while they remain the bad guys.
2 - As You Were - Yes, I know the plot revolves around Spike having the idiot ball, but I just like that we get an update on how Riley is, and that he's happy. Because I like him, and it was just that he and Buffy were not good for each other, or rather, Buffy wasn't good for him, and it's understandable given the cultural cues he grew up with and I just like that he's happy. Had Buffy continued, I would have been entirely happy with having Riley and Sam show up every two years going 'hi, we're fine, keepin' on keeping on' and so forth.
Day 1:
Favorite SeasonDay 2:
Favorite EpisodeDay 3:
Favorite Song Used In An EpisodeDay 4:
Favourite Female CharacterDay 5:
Least Favourite Female CharacterDay 6:
Favourite Male CharacterDay 7:
Least Favourite Male CharacterDay 8:
Favourite FriendshipDay 9:
Favourite RomanceDay 10:
Least Favourite SeasonDay 11:
Least Favourite RomanceDay 12:
Least Favourite EpisodeDay 13:
Favourite Potential SlayerDay 14:
Favourite Female VillainDay 15:
Favourite Male Villain Day 17: Character You Relate To The Most
Day 18: Character Who Didn’t Get Enough Screen Time
Day 19: Character You Like That Everyone Else Hates
Day 20: Best Spike-centric Episode
Day 21: Best Willow-centric Episode
Day 22: Best Xander-centric Episode
Day 23: Two Characters You Wanted To Get Together That Never Did
Day 24: Favorite Example of 90s Special Effects
Day 25: Favorite Buffyverse Saying
Day 26: Favorite Scooby Moment
Day 27: Cutest Moment
Day 28: Character You Love To Hate
Day 29: Episode You Hate That Everyone Else Loves
Day 30: What You Think Made Buffy So Great