Is it his powers? They are an impressive skill set, and do set him a cut above most heroes... but that isn't it. Ultimately, any writer could easily construct a hero or villain more powerful than Superman. What creators cannot do so easily is create a character as iconic as Superman.
If not powers, what sets him apart? Quintessential Superman actor Christopher Reeve once said "What makes Superman a hero is not that he has power, but that he has the wisdom and maturity to use power wisely."
Superman's greatness isn't just about his physical super feats - although those are astonishing - but how he uses them in service of others. It is his faith in us that makes him unique, and why he is DC Comics' flagship character. That is why his influence is felt strongly both within the context of the imaginary DC Universe, but also his impact in the real world.
Each one of these highlighted ten moments from Superman's eighty plus years showcase why he has an unparalleled position of influence in the DC Universe. Moments that put us in true awe of the character and say "That's who I want to be."