Is Hamlet the greatest dramatic character ever created? He is a man of radical contradictions; he is reckless, yet cautious, yet uncivil; tender, yet ferocious.
First, one could question your assumption. “Taxonomies are never innocent”, and putting Hamlet on top of Oedipus, Faust, Casanova, Hedda Gabler, etc. implies a prejudice toward English literature that is not universally shared. Even Lear can claim highest honors in some scholarly circles, to say nothing of Willie Loman or Stanley Kowalski, or Vladimir. However, having said that, Hamlet is indeed a complex character, especially if you ascribe to the theory that he is indecisive rather than duplicitous. His monologues, which by convention reveal his real character, show him to be introspective, a bit of a misanthrope at time, yet at other times quite complimentary toward humankind (“Man delight me not, no, nor woman either…”; “What a piece of work is man”), fairly unforgiving (“So Rosencrantz and Guilderstern go to it…”), rashly quick to act (for example, stabbing the figure behind the arras) yet patient (as when he passes up his chance to kill Claudius at prayer), cold and remote in love (as with Ophelia) but warm-hearted toward Yorick’s memory. But all dramatic characters are multi-dimensional, and act out of a variety of motives, many of them contradictory; their complexities are what make them interesting. The play’s rich language and its universal psychological appeal have garnered it much critical praise and many productions.