My first pick among the men would be Jimmy Stewart followed closely by Spencer Tracy. Others in the mix would be Paul Muni, who gets very little mention today, and James Cagney. Many people do not know that he was a great dancer. Check him out in his one Oscar winning role, “Yankee Doodle Dandy.” John Wayne and Clark Gable were much better actors than many people realize.
My first pick among the ladies is Katherine Hepburn followed by Elizabeth Taylor. They turned in great performances as they aged over the years. People don’t realize that as actors age, they become different people with respect to playing roles. It takes real talent to be able to still turn in a credible performance as they age. Betty Davis and Judy Garland also make my list. Had she not had the drug abuse issues, Garland would have been further up the list.
As for voicing cartoons, Mel Blanc was the greatest ever. Just about every male voice on the classic Warner Brothers cartoons.