You have to remember who it is you're talking to here. I am one of very, very few writers who makes a full-time living from my writing and who doesn't do anything else on the side. So there are people who are going to insist that this fact alone puts me in the camp of the commercial hacks. I think that attitude is stupid, but it is pervasive, and if you want to make money for your writing, you'd better come to grips with the fact that if you do, there are plenty of people out there who will be more than happy to call you a whore. What you need to remember is that the fact that they believe it doesn't make it true.
People write for one of three audiences.
You can do good work and write for any of these audiences, but you're just as much in danger of whoring your soul if you try to please academe as you are if you try to please your fans. And that may not become critically acclaimed art, or it may not become commercially successful art, but it will by God be art, and it will be yours, and you will sleep better at night for doing it. Depends on what you like and what your goals are. If you dream of being a novelist, start with novels and stick with them. If you want to be the next O'Henry, start with short stories.