Similar list apart from one show-

Phil Silvers Show (Bilko)
M*A*S*H
Police Squad
Frasier
Curb your Enthusiasm
Bakersfield PD
30 Rock
Seinfeld
Larry Sanders Show
Cheers

Not an easy task and I bet I've forgotten some that should be on this, but in no particur order these came to my mind first:

1. The Office
2. Friends
3. 30 Rock
4. Modern Family
5. Parks & Recreation
6. I Love Lucy
7. The Cosby Show
8. Curb Your Enthusiasm
9. Frasier
10.The Simpsons

Blossom!

1 Seinfeld
2 Bilko
3 Malcolm in the middle
4 King Of Queens
5 Bakersfield PD
6 Taxi
7 Alf
8 The Simpsons (when it was funny)
9 Married with Children
10 South Park

1.Friends
2.The Larry Sanders Show
3.Soap
4.Barney Miller
5.M*A*S*H
6.Scrubs
7.Two and a Half Men
8.Curb Your Enthusiasm
9.Sergeant Bilko
10.Roseanne

I guess nobody watched Ally McBeal

Ally McBeal was a comedy-drama.

Ooh, as an American now living in England, I'd like to throw in a potential top ten. I know as soon as I click 'post', I'll think of another one which should have made the cut. But, here's an earnest attempt:

10. Malcolm in the Middle
9. Roseanne
8. The Golden Girls
7. Friends (though the final couple of years got a bit stupid)
6. The Cosby Show
5. American Office
4. Strangers with Candy
3. Parks and Recreation
2. Arrested Development
1. 30 Rock

I couldn't help but do a separate list for toons as I love too many of them.

10. Dr. Katz
9. Futurama
8. Harvey Birdman
7. Sponge Bob (had to buy the film on DVD because it was straight up awesome.)
6. King of The Hill
5. American Dad
4. Bobs Burgers
3. South Park
2. Archer
1. The Simpsons

Great but don't really qualify as sitcoms: Daily Show, SNL, Exit 57, The Colbert Report, Just Say Julie, Viva Variety, Nurse Jackie, Space Ghost: Coast to Coast.

Meaning to watch: East Bound and Down, Always Sunny in Philadelphia, Community...

dont forget Welcome back Kotter

I'm sorry for all the animations in here, but to me the american animations have the best writing.
1. The Simpsons (Sorry for Cleshay)
2. The Larry Sanders Show
3. Seinfeld
4. King of the Hill
5. Curb your Enthusiasm
6. M*A*S*H
7. Arrested Development
8. Dick Van Dyke Show
9. Cheers
10.Futurama

Ooh more lists, I like a list.

1. Seinfield
2. Arrested Development
3. Weeds
4. Curb Your Enthusiasm
5. It's Always Sunny in Philadelphia
6. Frasier
7. Big Bang Theory
8. Parks and Recreation
9. Home Improvement
10. 30 Rock

Seinfeld
M.A.S.H
Fraiser
The Simpsons (the most recent series is fantastic)
Spin City
Home Improvement
Futarama
Cheers
Taxi (purely for the inclusion of Andy Kaufman)
Dinosaurs

Friends and How I met your mother

Did no-one like Scrubs.
I can' believe no-one has included it while they included so many shows that I sat through in stoney silence!

Scrubs was good, at times very funny, though it leaned rather too heavy on the 'learning' and 'moral of the week' sort of thing. There's only so many times you can see JD's face get serious and his voiceover pronounce 'oh no' as we head into the ad break.

Still, when it was trying to be funny, it was very good. I wouldn't put it in a top ten of American shows myself.