The Cosby Show...

That and any Shark-jumping kid-adding show you can name.

Married with Children, Arli$$

Drive

X Files

I think the Simpsons breaks the record. I can't believe i was in middle school when it came out, and i'm 32 now! That show is going to outlast me!

Lost

Prison Break

I think you can argue based on the quality of season 3, Veronica Mars may have been better off getting canned after season 2. I'd also suggest that the year without ASP on Gilmore Girls was one year too many.

Tru Calling lasted about a season too long. The pity there, of course, was that it actually got to the point of executing the premise pretty well within the last 8 episodes or so (the last of the first season and the whole second season).

Friends

ER
Everybody Loves Raymond

The Simpsons

The UK Coupling should've ended after Season 3.

M*A*S*H*

Without a doubt.....THE X-FILES

Another vote for X-files. Such a great series, but the thing that sticks with me the most about it is how it just limped across the finish line.

CSI shows

Roseanne
Seinfeld

Just Shoot Me

Wow, I couldn't disagree more. That show was still golden in its final season, and it probably could have gone on for at least a few more if you ask me.


ER
Roseanne
The Simpsons

X-Files of course and Happy Days.

I think the show should have been cancelled after the first episode. Overrated show Beyond belief. When people call Seinfeld the funniest, greatest show ever I wonder to myself if people have ever watched anything else besides it.
Sorry to go off-topic but good lord why do people find it the funniest show ever? Scrubs, The Larry Sanders show & newsradio-now those are the funniest most brilliant show on TV.

The Simpsons
Law & Order (original)
Roseanne
The Jefferson's

Oh yeah - how can anyone forget The Facts of Life?!?!?!

7th Heaven...

It's hard to be objective anymore because nearly every show after Seinfeld has stolen something from it. Whether it is a little joke, an idea, a character, a scene, a particular delivery... it's hard for the original to stand out when it has been copied to death, and you don't even realize what you are watching was done before, and oftentimes better. It was the first of its kind. The original is always better than the copies.

Friends is the biggest offender. I can find something in a majority of episodes that was done before on Seinfeld.

I love Seinfeld, but I think the last season was considerably weaker than the previous ones.

STILL, as the old cliche goes, it was better than most sitcoms on at the time.