I look at the overall trajectory of quality. As I said, there was some good stuff, if not great stuff through that period, but whenever something great happened something equally horrible came after that killed any creative momentum.
For instance we went from the Casey AOS run , followed shortly thereafter with Chuck Austin's ACTION disaster. We got Busiek and Johns good runs and build up to NK a only to see it pissed away and undone with the actual execution of NK and then of course, GROUNDED. Not to mention the continiuity quagmire that resulted from BIRTHRIGHT being will nilly plugged in without any plan, destroying what was up to that time was a pretty solid continiuity that had ran from 1986.
The one step forward two steps back momentum and the incomprehensible continiuity combined just kept the Superman franchise pointed in the wrong direction. It doesn't discredit any of the stories you mentioned, but as a whole the era was a disaster that the character will be spending years yet to recover from. Of course, your milliage may vary.