Heroist
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Eh, well, it's not quite defined that way; everything is subjective for everyone. In short, for a beginner there are about a dozen titles you can check out (by choosing an interesting genre) and only then draw a conclusion as to whether it's worth continuing; like, say, Death Note, Fullmetal Alchemist, Hellsing, Berserk, Naruto, etc. Basically, things you might have heard of even without getting into the subject.
Whatever