Dad's Army, Only Fools & Horses, Porridge, Father Ted are the best.
The list has quite a few 90's sitcoms that were decidely mediocre.... 2 Point 4 Children and Goodnight Sweetheart. My Family was only saved by Robert Lindsay and the actor who played the oldest son (who went on to an illustrious acting career doing cringeworthy ads for BT!). The Thin Blue Line was pretty poor... was that the last sitcom Rowan Atkinson did? Gimme Gimme Gimme I couldn't stand.
Does Minder qualify as a sitcom? Arthur Daley has to be one of the best TV characters ever.
I'll give honourable mentions to 'Allo 'Allo (anybody remember the Great Storm of 87 when a tree came down on Gordon Kay's car.... put an end to his career if I recall correctly), Steptoe & Son, Open All Hours (Ronnie Barker was a comic genius, and of course David Jason before he was Delboy).
Til Death Do Us Part.... now Alf Garnet was a character.... I had a great uncle who went ashore at D-Day who was just like old Alf.... wasn't afraid to call a spade a spade
As regards the goodies, there were a couple of episodes recently aired during the '50 years of BBC2' season. I had forgotten how funny this programme was. Can't understand why it hasn't been repeated at all.