Even though I've probably seen every episode about ten times, I still think this is the best TV show ever. There never has been or ever will be a show with such clever writing and a keen sense of humor.
The actors on Seinfeld all work well together, so of course that helped. The main characters were fashioned after people in the show's creators (Jerry Seinfeld and Larry David) lives. A nine year run isn't too bad for a show that was initially pitched as "a show about nothing".
That is why they called it a show about nothing! It is pointless much of the time but has very unique topics. The characters are idiots with some of the most humorous results such as the whale and the golf ball. I can still see that guy in the ocean on the back of a whale. That shows good writing and acting because that scene never really happen and they did it without special effects. I think that all four of the characters belong in prison.