The list is very US Centric. And I'd forgive it that if all it was was US shows... but the inclusion of Ab Fab, Monty Python and Downton Abbey seem to imply that it is a much broader list.
This is a bit out of whack, because I then find myself wondering: Where is Black Adder? It's hard to...
The Writers Guild of America polled their membership for the top 101 TV shows written.
http://wga.org/content/default.aspx?id=4925
#1 was "Sopranos"; followed by Seinfield.