It's generally accepted that, although they're all difficult, the general order is (from least difficult to most difficult) is 3-1-2-4. But, of course people are different. My teacher for instance, who graduated from the university of Indiana for his undergraduate, and went to graduate school at the Royal Academy in London, (and who has played and performed all four ballades) said that for him, the difficulty was (from easiest to hardest) 3-4-2-1. He also said Chopin just doesn't fit under his hands well, whereas Schumann and Beethoven do.
So, I'm curious if anyone has other experiences.