My picks are not going to be the norm b/c I don't find a lot of stuff on the networks groundbreakingly funny. The Office is the only one I can single out, and it was done (slightly better, IMO) by the Brits first. I like The Simpsons and Family Guy, but cartoons are too easy. So, I'm sticking to live action sitcoms.
Red Green - Harold rocks!
SCTV - the blueprint for sketch comedy shows
Leave It To Beaver - not cutting edge, but still a must-see for me when it is on.
Cheers
Seinfeld
Taxi
The Mary Tyler Moore Show
Particular favorite sitcom episodes of mine:
The Bob Newhart Show (the one in the New England inn) - final episode
Seinfeld - "The Competition"
WKRP In Cincinnati - "Turkey Drop"
The Mary Tyler Moore show - "Chuckles Bites The Dust"
Taxi - "Reverend Jim: A Space Odyssey"
The Dick Van Dyke Show - "It May Look Like A Walnut"
The Honeymooners - "Chef Of The Future"
And finally, one that is before my time even, but worth renting or checking out if you are lucky enough to have a local station running it at 3am:
Sgt. Bilko. This show is the blueprint for every TV sitcom made to this day. Still considered by many, including those who make sitcoms, to be the best sitcom ever made - better than Lucy (I hated Lucy), Seinfeld, Mary Tyler Moore, Dick Van Dyke, etc., etc.