Ron Howard has often said his favorite episode was the one where he nured a bird to health and then had to let it go.
Note that his movie production company is named "Skylark" after the bird.

I love the old Andy Griffith episodes, and agree it jumped the shark when Don Knotts left.

Perhaps the worst character in televiion history was Barney's replacement who lasted a whole season. I forget the guy's name.