You have a child mind. Just because a character consistently wins or just looks cool doesn't mean he's the author's favorite. Much more important is the attention of the author to the personality of the character. The extent to which the author himself is interested in it. Authors' favorite characters often suffer the most lol. By the way, Sanji is definitely one of Oda's top 5 favorite characters. Zoro is not even in the top 10. Oda just gives what his fans need. If you're interested in a character, you're doing what's not for the fans, but for you. And yes, an author's love for a character is not the same as a reader's love for a character.