'Screwfly Solution' - best sci-fi short story ever?

'SS' actually ties with Jerome Bixby's "It's A Good Life". The fact that I enjoy these two so much might explain why 'relationships' aren't my strong point

"Actually, that's because you're a dirty dog"

one I like a lot is Ted Sturgeon's "Mr. Costello, Hero," a thinly veiled portrait of a Joe McCarthy type who goes around tape-recording conversations (which he innocently refers to as his collection of voices) and using them to blackmail people into following his orders. what makes it so creepy is that the narrator really likes Mr. Costello and spends all his time defending him.