I’m sure Oda has said Buggy is his favourite character.
Like look at the other four. They are all designed to be liked, in a broadly similar fashion. They have a cool design. Scars. Powerful fighters. Manly attributes.
Then there’s a literal fucking clown, a starter villain who’s a shit, a liar, a bit of a coward… and Oda keeps letting him rise further and further to positions he doesn’t deserve. Because Oda really likes him.