To each their own. Without even talking about nakama potential, Yamao as a character still sucks donkey cock. She's absolutely terrible and if you were to remove all of the Nami features and replace them with that of Chiffon, you'd take out 95% of the her fanbase. There's a reason her fanbase is composed predominantly of horny simps and trans activists.
Anyone would tell you that Carrot's not the best character by any stretch of the imagination, but you gotta laugh at the hypocrisy of people hating on Carrot for being an admittedly feebly written character when they're on the other hand creaming their pants over the sentient shit stain of a character that is Yamao.