Well as I've already said my favourite show is Buffy, so only question is what is my favourite episode from the show. Without a doubt, it has to be the one with these chappies:
Hush is one of the most beautifully artistic episodes I have ever seen on any show. The whole town wakes up one morning unable to make any sound. After research is completed it is found that this was brought about The Gentlemen who remove a population's ability to speak in order to get away with making off with people's organs.
The performances are amazing as the actors have to push the plot on and express so many emotions with facial expressions alone, and they achieve this brilliantly. The fact this episode came in the middle of the weakest season makes it all the more impressive.