The single funniest individual television episode is episode four, season one of the British The Office. This is the staff training day episode, when David Brent goes home to get his guitar. There's nothing better.
When comparing the British show to the American, here is what I see in the four main characters: Dwight is an American caricature of the more realistic Gareth, Pam is a peppy version of Dawn, and Jim is less a loser (and less charming) than Tim. But Ricky Gervais' David Brent is so wholly original, so wholly real, and so wholly annoying, Steve Carell just had to make his own character in Michael Scott. They share similarities, but their essence and their mannerisms are separate identities.
I continue to praise the death of the laugh track in the sitcom.