Trafalgar Law. I like his mannerisms and how funny he interacts with others.(Especially Luffy). I love that he continued to live on despite his rough past and tried everything he could to avenge the only person who looked out for him. His powers are dope AF, hat looks cool and his Jolly Ranger is too. There's not anything I dislike about the guy, he's pretty well-written overall IMO
There are plenty of good and awesome characters in One Piece that I like but so far, Law is my favorite.