For me its sanji. Not like other characters have improved or anything pretty much every character became pretty boring and don't feel like are that important anymore, but he has fallen down into abyss for me. Even luffy as the main character is probably one of the most boring character for me right now. I guess I am only interested for an all out zoro fight after that I will stop caring about pretty much all the current SH characters. Zoro being consistent in not having much screen time is a good thing for him I guess, since oda couldn't screw his character if no screen time.
Others get screen time but usully go into negative due to same repeated shit