Hmm. Good question. I haven't taken any literature courses at an MA level, though I did take one literature course that was a hybrid BA/MA course and had both undergraduate and graduate students in it.
To be honest, most of my course choices were motivated by what I needed to take and what would fit in my schedule. There were a few classes I took that weren't my first choice, but were the most practical choice. Sometimes, those unexpected classes ended up being the most interesting ones, because they introduced me to topics that I might not have pursued on my own. I took a few classes on authors or literary periods that I already loved and was familiar with, and they were rewarding, but I don't think I got quite as much out of them, to be honest. Though, I'm glad I took those classes while I had the chance. I got to study one of my favorite authors with a professor who was an expert on him. How often do you get a chance like that?
In terms of what literature classes I found helpful as a writer, that depends on what you mean. Academically, I found that most of the higher level classes were good for pushing me to write longer, more original, and more narrowly-focused papers. I imagine it's even more like that in grad school. In terms of the readings themselves enriching me as a writer, I don't know. I think reading great books is always valuable for a writer. But some of the classes I found the most valuable didn't directly contribute to my writing much. For example, I loved studying Chaucer, but I don't find medieval literature that inspiring for writing. I found I was most inspired by the classes where I read some more contemporary writers, because their styles and the content of their stories were more likely to be close to what I aspire to as a writer, if that makes any sense. For example, taking a science fiction class revived my interest in trying to write my own science fiction.