However, the statement itself seems incomplete or out of context. It would be more natural to say:
* "Tu es mon meilleur ami dans le monde." (You are my best friend in the world.)
* "Vous êtes mon meilleur ami dans le monde." (You are my best friend in the world.)
The first phrase is used when talking to a friend in a familiar and informal setting, while the second phrase is used when addressing a friend in a more formal setting.
Please provide more context so I can give you a more accurate and helpful answer! 😊