Williams was good in concert, but the funniest guy I've ever heard live was Rodney Dangerfield. I never saw Berle. I've found most comedians are far funnier on stage than on television. At least, the ones I've seen are.
One of the best routines ever was Bill Cosby's "stop it" routine.
Agreed... Two of the funniest "old school" commedians were Alan King and Buddy Hacket. Unfortunately, many of us never saw them live, only on "The Tonight Show," with Johnny Carson. They were good, and funny, but I've since seen some clips of them doing their standup acts, and they were a scream! And Buddy Hacket was really something of a "potty mouth!"
Mark