Hi,
If you follow suggestions from seniors, you will find out that US History has a very typical and relatively lesser syllabus which is easier to cover. Furthermore, no matter how hard paper maker try to mold or twist the topic, he cannot go far away. According to this logic, I think US history is relatively easier.

In case of Gender Studies, we can come up with more logical reasoning if we have a little concept of the basics.

So overall, it depends upon your interest towards subject.

I am opting both, so I think both are easier than other subjects.