Consider two things when deciding whether to write your next novel in third person or first.

1. Which way are you most comfortable telling the story? Some stories naturally lend themselves to either first or third person, usually due to the complexity or simplicity of the story.
2. Which person do most stories similar to yours use to tell the story? Readers expect a story to be similar enough to others of the same genre that they will react negatively to something different. And, if you are going with a traditional publisher, they may require that your story be written one way or another, again depending on how it’s usually done in the particular genre you’re writing in.