who is the protagonist in the novel 'To Kill a Mockingbird'?

This is an interesting question. I have heard many arguments between Scout and Atticus being the protagonist of the novel. Scout tells the story in retrospect but much of the power in the novel hinges on her father Atticus. I'm inclined to say that Scout functions as a stronger protagonist. it’s her coming-of-age that seems to bring all the events together into a narrative that includes the reader in the goings on in Maycomb.