I have been told that math would also help in English and other humanities as well. Statistical analyses of literature, as well as things like procedurally generated narratives, are beginning to take root. Literary/artistic criticism through the lens of neuroscience/cognitive psychology is also ready to take off, so many of the scientific fields listed above would be useful.

This is not to say that I think that a focus in humanities will lead to the greatest personal utility, but if you feel that you must do something in that vein for a career, then a background in hard science/math would be a good thing. It will make you quite unique and valuable, something that you will need if you enter that horribly over saturated market.