Anytime i hear that "Que Sera Sera" song I always think of Barts Comet episode no matter what, even though it was obviously much older of a song than that episode.
Certain eps will be classic no matter what since I remember them so well:
"Bart On The Road" (I'll always remember them going to that Dome highrise building in Knoxville TN and it was full of wigs.. Plus I always think of this ep when I hear "Radar Love")
Bart Sells His Soul (Radioheads "Pyramid Song" reminds me of that dream of Barts where hes rowing on water along with a bunch of other spirits, except he doesnt have a partner like the others.. one of those scenes that always stuck with me. Someone needs to make a video of that scene with Pyramid Song)
The first episode/Christmas episode (I remember seeing it when it came out.. My family was working class/middle class and we related to the difficulties families face during christmas on this episode.. it was a pretty powerful ep for me as a kid, there wasnt a show really like that at the time, especially animated. I then began recording other episodes on VHS for the first 2 or 3 seasons, then stopped for some reason)
Homer Badman, Bart Gets An Elephant, The Otto Show, A Milhouse Divided - these episodes among others that I can't think of right now simply were ones that made me laugh a lot. Homer Badman is def one of my favorites. Still relevant today on how ridiculous and sensationalist the media can get.