Michael Pollan gives a masterclass in selecting a narrative voice in the most recent episode of the Longform podcast.
You have to reconstruct your first person [narrative] every book…. Your personality has so many elements, and you don’t use all of them. You pick a few…. Some facts about you are irrelevant to that story…. You have to take out of the whole grab bag of what you are….and you cobble together a first person that consists of several of them…. They’re all true, but you get to choose…. Are you going to write in the first person or not? … Which first person?