Seinfeld, was a funny show I didnt realize it until it was off the air and I was watching the sindications while I was in college.
But for number one of all time, I would have to go with "Martin"(Martin Lawrence). Almost every new sitcom that I see these days does something that Martin invented. Think about it, how many times have you heard someone say "you go girl!" on a tv show, Martin's the one who started that played out saying. You even hear it on some of the white sitcoms every now and then in order to get laughs. As well as Martin demenor is copied by some characters on shows.
And "Everybody loves Raymond" might be the best on TV right now.