Year ago, when I was working as a librarian in a New Jersey College, an English professor talked to me about the dwindling number of students in his courses about Joyce, Woolf, Eliot, and other post-moderns. “They just aren’t interested,” he complained. “What do you like to read for pleasure?” I asked him. He said, “Mysteries. Detective fiction. I love them.” “Well,” I said, “have you ever considered offering a course on mysteries and detective fiction? You know, what makes for a good one. The history of. The best writing. And so forth. Bet you would get students for that.” 
He was shocked. “I could never do that,” he said. “I’m an English professor.” Alas, his courses continued to dwindle until, in time, he was dropped from the college.
Writers are always looking, searching, for what to write. There are many reasons to choose this or that subject, style, and/or genre. But I would suggest you should always choose what you most like to read, what gives you the most pleasure. You know the subject, style, and/or genre because you read it for pleasure. Therefore, you have the best critical apparatus to shape and critique your own work. And because you love it, you know its capabilities, language, style, and form. It’s all very well to write what you think is wanted. Write what you enjoy and it is more likely to be wanted.