Spike burning to death. AtS S5? La-la-la, I can't hear you! 😀
"Bewitched, Bothered and Bewildered". All of it. "Doppelgangland" except for not killing Vamp!Willow, that was lame. Willow/Tara except for S6. Xander vs Cordelia, the snark battle of the century. The songs in OMWF, the plot is terrible but the songs rock. "Prophecy Girl", "Becoming".
All the precious Scooby friendship moments like Buffy tackling Willow to the ground with a hug at the end of Choices. Or The Scoobs watching an Indian movie in Reptile Boy. Or Giles and Cordelia annoying each other during research party in Killed By Death. Or Willow encouraging Anya in Triangle with the words "I have faith in you, there is nobody you can't piss off". Or Dawn becoming all squee-y after seeing Willow and Tara getting back together. This is what makes me rewatch the show, despite being so grumpy about like half of it.