Treehouse of Horror VII is my pick. (Only the first segment.)

Nope, I may refer to what if any "Treehouse of Horror" is really canon rather than being a fanon

First one

Technically the 1st, 2nd and 3rd treehouse of horror episodes are canon. Not the "stories" but more of the interstitials (example: Bart and Lisa in the treehouse in TOH1, the simpsons eating candy in TOH2)