Might be the wrong question to be asking in determining your fourth year schedule. For what it's worth, it would be a much better use of your time to take electives to help you to decide on your career path, or, if you have already decided that, to solidify your standing in the Match.
But, with that said, I expect that you'd get more use out of a radiology elective, to review anatomy and see a broad variety of disease. Derm would help as well, but in a limited way. I took neither and did extremely well on CK, though.