The best performance was by Lee J. Cobb
After the dust settles and the novelty of Brando's performance wears off or worse: is parodied so much, I'd have to say that Cobb gave the best performance in the film. Johnny Friendly was the main villain of the piece, but Cobb chose to humanize him. He could be mean and threatening, true, but he could also be charming and fatherly to those he valued. It's the humanization of the VILLIAN that makes the film as powerful as it is.
There is no "off" position on the genius switch.