This is a tough poll. Great choices, I loved all of them and like juhful mentioned it's missing All in the Family.
But I'd go with Seinfeld. Firstly because it's a mentor to probably the most popular T.V series ever, F.R.I.E.N.D.S. Infact the latter picked up some great bits from Seinfeld [some might say the latter is a rip-off of the former, but I wouldn't go that much]. Friends was mostly loved by women bringing in that romance angle and more about relationships, which Seinfeld got rid-off and concentrated more on comedy and containing an episode within itself, which made it more re-watchable. Both are about a group of close friends in N.Y City where the setting is basically a coffee shop or a room, but Seinfeld definitely had better script. Infact it became the runner-up in the 101 Best Written T.V series in the Writers Guild List. The first was awarded to The Sopranos, but it's not a surprise about Seinfeld coming in close, because each Episode of Seinfeld represented something that happened in our daily lives. In fact it called itself, A Show About Nothing, but which meant A Show About Everything. The slapstick humor, the characters, the setting, the stories intertwined in their daily lives across each episode, everything is memorable. "The Contest" an episode in Seinfeld also won the Best TV Episode of all Time in the T.V Guide's list and the show's producer Larry David a primetime Emmy award for Outstanding Individual Achievement in Writing in a Comedy series.
To all first-timers to Seinfeld, I'd like to say, get past the first 2 seasons for just understanding the characters, and you will definitely have the Best T.V Comedy you can ever watch.
