"The Snuke", easily. "24 Minutes" may not have actually been going for an all-out parody. I have to assume that, at least. It was more of an homage. The South Park episode did more things that actually parodied the show -- putting a funny twist on its conventions. Examples of that are the split screen that turned out to be showing two parts of the same exact shot/location, the "not anymore you're not" scene, and the power going out and resetting the time to 12:00. The scene in the Simpsons episode that most resembled that was the "collapse your splitscreen" thing, which... actually didn't make much sense, joke-wise.
Dude, think before you post. Have you even seen the South Park episode we're talking about?