The Simpsons. Even though it fell off its peak long ago it is a culture defining show and still one of the most quotable off all time.

30 Rock. So consistently funny with a great cast and had the advantage of being a comedy about making comedy.

Seinfeld. All the same reasons as 30 Rock. Helped pave the way for shows like that.

Married with Children. I have so much nostalgia for this show. Was boundary pushing for its time. A personal favourite of mine.