I don't think it's near the end but Family Guy is as good, if not better, than it was in the beginning.
The Middle
This is a show I can't get tired of. We watched it as a family the first time and me and the kids watch the series over and over again (watching right now!). I am so bummed they ended this show, it totally could have kept going.
Brothers and Sisters is another one I have watched several times. Probably my favorite drama, such an amazing cast. Love that show!
90210
Smallville
Loved this show and especially Kyle ChandlerFriday Night Lights! While I preferred the earlier cast, I loved this show right to the end.
But that was the ugliest wedding gown I've ever seen on a sitcom.The Golden Girls
Although most fans agree that the Connecticut episodes were inferior to the New York City ones, when I Love Lucy aired its final half hour episode in 1957, it was still the number 1 highest rated show of the season. So I would say it qualifies. It left the air on top.