Q-Jei

I know right. That's feels tough get right now

After everything she's been through, I must admit that Robin is a character I admire a lot. Despite her glaucous sense of humor, she's smart and has a very developed analytical mind that allows her to be successful in almost everything she undertakes. Needless to say, she progressively won admiration from the other Mugiwara over time. If it was her instead of Luffy as the main character, she would have probably been the perfect Mary Sue of One Piece in my opinion. The "Demon Child", as the World Government calls her, clearly has an exceptional moral sense for the universe she's in. It's such a shame they want her dead.

In terms of "Mary Sue", a really decent and written character, because she has flaws (a typical Mary Sue doesn't have any one or 1-2 meaningless ones)