"It's The Man of Steel versus...The Man!
Huh...you know, Peter David once pointed out that SUPERMAN IV might have been a great Superman movie if one scene had gone radically different:
Chris Reeves, as Superman, is at the United Nations, and giving his speech against nuclear weapons, and how he will dismantle them all.
In the movie all the delegates clapped...but what if they didn't? What if they cursed Superman down, and Superman said "I'm going to do what I think is right anyway?"
What if this led to a situation where you've got Superman vs. the World?
That might have been an interesting film! Superman's greatest strength as an adventure character is that he is an idealist, the kind of guy that doesn't make little compromises in order to be pragmatic. He's also so powerful that Superman has the ability to do what he wants without anyone telling him he can't...which would make a story like the above scenario for SUPERMAN IV rather interesting.
The problem with most stories of this type where Superman uses his vast powers to make a difference (e.g. KINGDOM COME) is that the power goes to Superman's head...I don't think that would be how it would work, because as said above, Superman's most interesting personality trait - the SOURCE of the above conflict - is that he doesn't compromise for practicality.
Superman has a tendency to be cast as the bad guy when he starts monkeying around with human affairs, but in the specific instance that Peter David was talking about (Superman removing all nuclear weapons), it's hard to imagine how Superman removing our ability to make the human race extinct would make him a "bad" guy...he'd be doing the noble thing, but also he'd be conflicted because he's sworn to obey and respect human law and human authority, who now are after him.