I voted Three's Company, despite the fact that it's going to bow out to The Simpsons. I am a Simpsons fan. Huge fan. But I'm a HUGER fan of Three's Company. This show made sexual innuendo and physical comedy relevant in a time where shows were struggling. The late 70's seen the end of shows like Happy Days, All in the Family, and other classic shows. Three's Company was a highly rated show that went through more cast members than any show I can recall during it's tenure.
Think about this. The show had a run of approx 7 years. THREE different women came through as Janet and Jack's roommate. Chrissy, played by Suzanne Somers; Cindy, played by Jenillee Harrison; and Terri, played by Priscilla Barnes. Despite those three girls not being as good as Jack or Janet, the show thrived. It also had The Ropers and Mr. Furley, played by Don Knotts, who is a classic comedian.
I'll vote Three's Company here. And for the record... it's sad that shows like Seinfeld, Cheers, How I Met Your Mother, and Family Ties bowed earlier than they should.