Given those choices, I would have to say the grave digger. Throughout the play Hamlet has thought a lot about death and what happens after death. He has questioned suicide. He grows in his understanding of the reality of death and how death is the great equalizer of humanity. Everyone, no matter how important or common will eventually die and return to dust. Alexander the Great and Julius Caesar are the same kind of dead as the most common beggar. Once Hamlet realizes this, it frees him a bit. As he literally holds the skull of Yorick the jester -- a man he knew personally -- death moves from theoretical to real. The grave digger, because of his profession, has come to this understanding of life and death very early in life. He is practical about death. It isn't a lack of care or concern for the dead, it is an understanding the dead are gone in spirit and are merely returning to the natural state of matter.
After Hamlet's conversation with the gravedigger, he too realizes better that "what will be will be" and that there is only so much in life that he can control. He tells Horatio, "there is a divinity that shapes our ends rough hew them how we will." The grave digger would certainly the world in the same way.