One way to categorizing fictional characters is by the character alignment system. Originating in the fantasy tabletop game Dungeons & Dragons, this system involves nine different alignments consisting of combinations of good, neutral, evil, lawful, and chaotic. Most anime characters can also be sorted into this system.
Let's take a look at one of these alignments: chaotic good. Chaotic good anime characters don't care about obeying rules or keeping order - they make their own rules, thank you very much. But while they don't feel the need to uphold structure, they're also well-meaning, kind folks who will do anything to help the people around them. If this sounds like nearly every shonen protagonist ever, that's because most shonen protagonists are chaotic good, which is why you'll see Luffy, Edward Elric, Ichigo Kurosaki, and more on this list.
These characters are a lot of fun, and though they can be frustrating to the more lawful among us, they're loyal where it counts. Which of these characters is the best? That's up to you to decide.
While Ichigo Kurosaki can usually be found helping others, he's insistent that he only does it on his own terms, not on those of other people. In fact, he'll even go so far as to help people who don't want his help - like when he rescues Rukia by destroying Soul Society's social structure, even though she asked him not to.
Katsuki Bakugo doesn't listen to anybody except himself, which makes him impossible to deal with on team missions. Nevertheless, he wants to be the greatest superhero the world has ever seen. Though this goal is partially based on a desire for power and glory, he also has a genuine desire to save people.
Kallen Stadtfield, also known by her real name, Kallen Kozuki, is a guerilla warrior working for the liberation of the Japanese people from the Britannian empire. She could probably live peacefully and avoid conflict, but morals are more important to her than peace, and the only way to live by her morals is to break the rules of society.
Kagura will ride into your house on a giant dog, then eat all the food in your refrigerator and go to sleep on your couch. But despite behavior that seems to defy logic, she has an inner moral compass that keeps her from doing anything she finds morally abhorrent, and keeps her on the side of fighting for good.