I don't think you can compare their performances because they are too different actors.
CBale is always looking for some challenging character. He always gets 'serious' parts, and as a person he is also way too quiet and reserved. Ex.:his performance in 'The Machinist' shocked me, did you see what risk he took to play the character???
RobertDJr on the other hand is more loose. He is a comedy actor, not entirely, but his characters are always fun and crazy. Iron man is a good example, or the movie he made with Sibyl Sheppard, I think. He is known for these types of performances.
I love Robert because he always entertains me, except in Holmes. I don't know why i didn't like him there.
CBale, can pass from an action movie to a drama one to a sci-fi and change the character, but I feel that Robert plays the same character or personality over and over again.
I gotta choose CBale. His performance in The Empire of the Sun got me and I think he is the best actor.Sorry Robert!!!
Hope it helps! ;)