Hemingway is one of the highest points where greatness in literature could ever reach. He was among the modern writers who are called "The Lost Generation," and an intimate witness of wars and conflicts. He was in a constant fight in himself and outside there were enough conflicts for him to tell the story of.
To me, his best work is: A Natural History of the Dead, a very short story where I could find all his philosophy as to the life in reality; a life which stands naked, cruel and vulnerable.
What is your pick?