This was the first new KOTH episode I've watched in a while, and it made me think about how amazing it is that this show is still in top form after so long on the air, while the Simpsons was already getting pretty bad at the same time in its history, while Family Guy has been around half as long, and gone down the tubes twice as fast.
Both of the other shows have made me laugh more, but are definitely way past their prime. King of the Hill might not be quite as good as it was at one point, but even so, the consistent quality of this series is incredible (personally, I haven't noticed any drop in quality, but apparently others have). I'll definitely be sad to see it go, even though I didn't always watch every new episode.