Scott Tenorman vs. the Monorail
Though referential and easy to swallow in its current iteration, The Simpsons' high points are a notch or two above South Park's zenith -- or so the internet insists.
Time and Rolling Stone both declare "Marge vs. the Monorail" the best episode of The Simpsons, and for the sake of sparing ourselves an argument that could drag on for months, let's pretend to agree with them. The Season 4 tentpole offers 23 minutes of back-to-back-to-back gags written by bona fide comedy master Conan O'Brien. That's about all it offers.
The single greatest South Park episode -- according to my own instinct, and vindicated by a handful of "best of" lists -- is the fifth season's "Scott Tenorman Must Die." Penned by Parker and directed by longtime collaborator Eric Stough, "Tenorman" stays light and silly until a whiplash-inducing tonal shift in the final minutes. The big reveal masterfully blends hilarity with existential dread, all while providing Radiohead a legitimate reason to be on the show. It's magical. And while "Monorail" trounces "Tenorman" in terms of chuckles per second, The Simpsons hasn't mustered anything as clever as the Shakespearean twist of Cartman's ghastly victory.