for me, it's Monkey D. Luffy
Why Monkey D. Luffy?
Because, he doesn't care if his opponent is strong or weak as long as he will serve justice to anyone or save them, especially to his brother, Ace even though he will be facing the navy's admiral, he doesn't care about them as long as for his brother he does everything for him.
He always cares for his Nakama or his crew members because he save them one by one form zoro down to franky and that's the reason why his crew members love him and cared for him too especially when they landed to Thriller Barks and where they met one of the Shichibukai, Oars, Zoro asked Kuma to get Luffy's pain to transfer it to himself (Zoro) because he doesn't want their beloved captain to suffer more, Chopper was crying out loud because he thought his beloved captain would die from poison when they were about to bound on Big Mom's island. And to anyone whom he met on every island they owe and love Luffy very much. Even though he acts matured when it talks about battles or kicking some enemy's asses, Luffy is such a cute and silly person that's sometimes Nami always beat him for being such an idiot person. And also, he always believed in his dream to become the Pirate King, even if some other people laughed at him for his capacity or being capable, he doesn't care about those talks because for him he will follow his dream to become the pirate king no matter what happens.