Generally speaking, you are going to get more out of a class that you are interested in when compared to one you aren't.
That said, sometimes you find classes to be more interesting than you first thought you would. The instructor can be as important if not more important than the subject.
Also, consider what discipline will synergize with your major. For the sake of pure personal interest, you don't necessarily have to take a course. College is not necessarily where you learn, it is where you become certified to know things or to be familiar with certain intellectual disciplines.