Buffy the Vampire Slayer

I definitely agree with the "Once More With Feeling" love. Some of my other favorites are:

"Innocence" from Season 2 - Angelus and Jenny Calendar

"Bad Girls" from Season 3 - Buffy, Faith, and the first appearance of Wesley

"The Zeppo" from Season 3 - Xander saves the day quietly while Buffy battles an off-screen apocalypse

"Dopplegangland" from Season 3 - Evil vampire Willow!

"Hush" from Season 4 - Once More With Feeling's equal-but-opposite episode, an exquisitely tense mostly silent episode featuring The Gentleman, who are by far Buffy's best one-off villains

"The Body" from Season 5 - Buffy and Dawn deal with losing their mother in a perfect, perfect hour of television

"Seeing Red" from Season 6 - Poor, poor Tara

"Chosen" from Season 7 - Overall, I wasn't entirely thrilled with Season 7, but Chosen ended up being a great episode and more than a fitting send-off.