I think, before many of you speak, you need, or perhaps better said, the author of the thread needs to clarify what "best" means. Is is skills/powers? Is it popularity? Is it dollars in the marketplace?....etc, etc..etc.
My personal opinion....
Best powers? No; near the top, yes (of non celestials/skyfathers).
The comic book hero who's made more $more$ than any other? Yes.
The standard by which all others are judged? Yes.
The most popular superhero? Yes.
Sum them all up...and yes, whether you like it or not, Superman is the best in a "generic sense". This include Bats and Spidey, who are close seconds.
I was watching King Kong yesterday and a thought came to me as the movie began...It would be awesome to have had a new Superman movie set on that time where it belongs. I have the very first series from 1948 (1938 comics) and there is Clark Kent! The episodes are very low grade of credibility when he uses his powers but it's a cool adventure.
Superman is the best character ever, because he is the exact essence of a hero. No one comes close. I love lots of characters, but Superman brings a tear to my eye and that's no joke! Superman is the light......
Superman got drunk in Superman III and hurt a lot of innocent people. Hes also been bad in the comics and wasn't there some comic, Armageddon or something where kills a whole bunch of people? Anyway, Supes is cool and is the most popular. I define "best" as being the baddest and toughest and strongest and best fighter in the universe and also pure of mind and body. Superman is none of these. So he is not the best......
He's got too many weaknesses as well. I mean if you're gonna count what someone is born with or training involved and no superpowers, then Batman is WAAAAAAAAAAYYYYYY more best than Superman. He doesn't even have superpowers and he's AWESOME. I think he took out Superman in the comics too, didn't he?