Tell me, who’s the best writer? The best painter? The best pianist? Or who’s the most famous? The answer will be different for each person you ask.
Trying to be the best is a fool’s errand. The best in what? Who’s judging? Why is this a contest?
Getting better is far more practical. You can certainly work hard today to be a better writer than you were yesterday. Keep at it long enough, and you might become someone’s best.