This is not a shot, Fist of the North, but I thought it was just common knowledge that people knew Supes is the "ultimate" Superhero. When you say ultimate, to me, I read it as who is the epitomy of the ultimate superhero. When I read it to mean like that, there is only one, and whoever is second is a distant second. To me, it reads who is a good superhero, meaning good guy, with the best attitude, traits, emotions, feelings, etc, etc....not to sound too mushy.
I've only got one thing to say, the death of Batman or Spiderman, whom I consider to be 2nd & 3rd in this contest would never generate the buzz across the globe that the death of Clark had. That's about as simple as I can put it, and I think his makeup has something to do with that, not just his popularity.
Now, there may other more formidale "good" guys to choose from other than Supes to pick from if you were going into a fight with to cover your back, but that's not how a I read this thread.