I'm going to be predictable and say 'Fawlty Towers', because I've been watching it regulalry since 1975 - afriend had one of the very first VHS machines, and even now, it still makes me laugh out loud. The skill is the tiny plot bombs dropped at regular intervals which knit together into a squirming whole by the end - e.g. the 'two doctors' who are given a room without a bath - each time one of them goes to the corridor batrhoom, Basil is behaving oddly - to them - with good reason to the rest of us. The high level is compunded by their being only twelve gems ever made - pure, and possibly unbeatable, comedy class.