“The Andy Griffith Show” is Griffith’s best work — certainly his most personal. It was never out of TV’s Top 10 programs for its entire eight-season run, and it inspired a spinoff series, a TV movies and several reunion specials. Fifty years after it left the air, the reruns continue. Griffith never won an Emmy Award, but he was the guiding creative force behind the show, building it into a situation comedy with heart as well as humor — and shaping the relationship between himself and Don Knotts, as deputy Barney Fife, to reflect the relationship between two friends in one of his favorite radio shows, the comic serial “Lum and Abner.”