Well for ones currently still in production I'd say Red Dwarf but it passed its sell by date about three seasons ago after it reached its peak.
Right now I think one of the funniest is The Big Bang Theory...
Agreed, however I am hooked on reruns of "The Last Of The Summer Wine".
The three old gents are delightful and when the ladies have their afternoon tea and lift their cups in unison, I wait for it!