Of course there is no single degree that everyone would find difficult. From this perspective, the subjective view is correct.
Nonetheless, looking at problems in life from this point of view is pointless. Humans come in all shapes and sizes with their own idiosyncrasies. As such, attempting to find an objective answer to a question given this context is impossible. And it is impossible for most questions contemplating the human condition.
HOWEVER, I am looking at this from the point of view of "What degree are students most LIKELY to find difficult". In this case, the degrees that cover the broadest range of academic disciplines would be the ones MOST LIKELY to be found difficult. Hence, why I mentioned Engineering/Law, because I feel this degree covers theory and application from both a numerical and verbal point of view. While there are plenty of students great at engineering, and students amazing at law, it is hard to find students who are great at both.
In answer to that, I would most likely not like it. I'm doing Actuarial/Law at the moment and I have to say, I have not particularly liked courses that cover the philosophy of law. As such, my exposure to the fine arts has not been all too positive.