I'm excluding American shows on the grounds that even the funny ones are too smug/sentimental to be enjoyable.
10: Steptoe and Son
9: Yes, Minister
8: Father Ted
7: League of Gentlemen
6: Fawlty Towers
5: I'm Alan Partridge
4: Rab C. Nesbitt
3: Blackadder
2: The Fall and Rise of Reginald Perrin
1: The Office
I never really watched Spaced enough to consider it for inclusion. Red Dwarf was quite funny but tarred by association with geeks.