Lets hash it out!
Love this topic. As far as Great fiction goes, I believe time is a major factor. What story still feels relevant after decades or even centuries have passed? Some works just don't age well while others remain painfully precise and clear long after the writer has passed on.
Fiction Greats are as much about the personality as they are about the work they leave behind. Richard Yates is a great example of someone who wrote great fiction but never got his moment in the sun. By the time he died most of his books were out of print. And his first novel was nominated for the National Book Award. But he struggled with his mental health for most of his adult life and I believe that definitely played a role in holding him back. He was in and out of institutions for most of his career as a writer. He even wrote speeches for one of the Kennedys during the 60's. But he was never able to hold it together for very long.
Compare him to someone like Kurt Vonnegut for instance, who also struggled in his own way but was able to build a career and hold down jobs and in turn, build a legacy. They were friends at one point. I think they might have taught together at Iowa. But while Vonnegut was able to build a legacy, Yates struggled just to get by. It wasn't until 10 or 20 years after his death that there was renewed interest in his work.