Great episode. I've maybe seen it one too many times though. The Simpsons has a fun pardoy of it in the Treehouse of Horrors II.
I have so many favorites from the original run of TWZ. It's hard to choose only one, so I'm sure I'll come back to this post and list others. But for now, I'll start with season one and choose "Mr. Bevis." It's a goofy episode compared to many of the others, but I love the message.
There are so many classic episodes though! I love them all. Well, all except "The Bewitchin' Pool." That episode can go straight to Hell. :-p