Treehouse of Horror VI. The 3 best stories from any ToH imo, and all in one ep .
First is with the billboards coming to life and causing chaos because Homer stole the giant donut, then the second is with Groundskeeper Willie killing people in their dreams, and the third is inside the 3D world with Homer showing up in OUR reality at the end. Awesome, awesome stuff.
This as a whole ep is my fav, but for single segments nothing can top The Shinning or Dial Z for Zombies for me.