The Dark Knight is the greatest superhero of all time
The best live-action superhero film of all time (The Dark Knight), the best animated superhero film of all time (The Lego Batman Movie), and the best animated superhero television program of all time (Batman: The Animated Series) all center themselves on one fictional man.
Bruce Wayne has studied 127 martial arts, earned 12 master's degrees, and perfected escape artistry. He can bench press 1000 lbs, catch arrows fired from The Green Arrow, has a genius-level intellect, and is an expert detective. He can anticipate attacks merely by paying attention to opponents' muscle movements. He is a founding member of the Justice League whose contingency plans against its members were used in a plot that nearly took them down by Vandal Savage. He somehow survives repeated fights with foes tough enough to stand toe-to-toe with the League, and has even fought Superman himself. He even manages to sneak around super beings, being including Superman. You know, that other hero that can hear in the vacuum of space. On top of his abilities, he has the greatest arsenal of gadgets and tools in comic book history (besides maybe Tony Stark). With enough preparation time, Batman can conceivably construct a gadget to get him out of any situation or defeat any foe.
Batman is the greatest superhero of all time, however, in large part due to his stories. Without question, he has faced many of the greatest super villains of all time repeatedly, such as Bane, Ra's al Ghul, and the Joker. Whether you consider The Dark Knight film, The Dark Knight Returns by Frank Miller, The Killing Joke, the "Hush" story arc, The Birth of the Demon, "A Death in the Family," or "Year One," Batman has provided comic readers with some of the best tales in comic book history.
Aside from these, Bruce represents the peak of human willpower. He has pushed himself to physical and mental levels high enough to compete with gods. The reason he is number one is because he should technically lose to almost everyone else on this list in a fight, and yet almost no one would predict him to do so. He doesn't kill anyone (for the most part), and yet always manages to find a way to defeat any opponent against whom he is pitted. No matter what happens to a person, be it witnessing his or her parents being murdered, being drugged, having his or her back broken, living a life largely deprived of love or intimacy, or watching the world literally crumble, Batman inspires all to adapt, cope, and persevere in the most hardcore and respectable way.