I voted for "Hush" not just because everyone, including the critics :iamwithst , says it is but simply because this episode is creepy. I mean, think about what it would be like not to be able to scream and raise alarm when something horrible is about to happen to you. If you can then you know what this episode is all about. Even with the creep factor it had funny moments between Xander, Spike, and Anya and also when the "Scoobies" are in the classroom and Buffy makes a stake gesture that gets misinterpreted. Classic Whedon! That haunting song sung by that little kid still sticks with me today.
Can't even shout, can't even cry.
The gentlemen are coming by.
Looking in windows, knocking on doors.
They need to take seven, and they might take yours.
Can't call to Mom, can't say a word.
You're gonna die-a-screaming, but you won't be heard.