Hulk vs. Superman has been an intriguing battle between comic book titans for decades. Why them, in particular? Well because of their often egregious feats of that most obvious and decisive superpower – pure, unadulterated physical strength.
Unless you’re a telepath/telekinetic of Professor X or Jean Grey’s caliber, you’d better have some degree of superhuman strength if you want to be effective battling bad guys.
Superman is not only DCs flagship superhero (he’s kind of like the Michael Jordan of the comic book universe); he may very well be the penultimate superhero in all of comic-dom.
There have been numerous copycats in other universes – from Prime, to Hyperion, Mr. Majestic, Gladiator, the weak-minded but ultra-powerful Sentry, Marvel’s Thor and Supreme. There have been quite a few more, but these serve quite nicely as representative of a superhero mold that has withstood the test of time.
The Man of Steel remains, nonetheless, quite unique among this stable of powerhouses. Superman’s strength is sometimes lifted as whatever numerical maximum the current author cares to list; but true fans understand that it is essentially incalculable – Clark is as strong as he needs to be and then some.
If nothing else, Superman is the savior, in a sense, and frail primates can depend on his otherworldly Kryptonian frame to see him through to an end that results in saving the doubly wise man.
It is usually either a love/hate relationship that readers have with Superman; either you love him for being the most powerful ally for whom you could ever hope, for being a relentless force for what is good and should be right in the world, or simply for being so damn powerful and giving you hope against even extra-galactic threats.
Or, you hate him precisely for the antithesis of those reasons – for being too powerful, for being too good, etc. If you’re a nihilist, then Superman is, in all likelihood, a hero you would rather see beaten to death.