You can't blame Singer for taking the Superman movie. If it wasn't for the first Superman movie, he would have never made the first two X-Men movies. Fox is to blame on the quality of X-Men 3 (good or bad).
And comics to film has always been a crapshoot. The original Captain America that was never released, the first Punisher, Fantastic Four (either one), Incredible Hulk, Daredevil, Swamp Thing, ect . . .
But good ones seem to be unlikely ones - The Mask with Jim Carey, Men In Black, Conan took some inspiration from the comic along with the novels, others that I can't think of at the moment.
Superman Returns is supposed to wipe out Superman III and IV, taking place 5 or so years after Superman II, from what I hear. I'm looking forward to it. It is Bryan's dream job and I'm sure he is making it his baby.