I agree with the guys arguing that it would be wonderful to get an emerging new talent writing a long run.
Looking at existing big names that might be tempted suggests that it might be worth considering Mark Millar? Red Son was good, and his run on Superman Adventures was excellent. And I know that he was very interested at one point...he had a 60 issue long story that he'd planned in fair detail, but one that required him to be in sole creative control.
Maybe too late now...his comics have now tended to become a wee bit stereo-typed and over dependant on slapstick violence? But then you could say same maybe about Garth Ennis, yet Garth seems to have a wonderful feel for Superman...and might be another candidate for a "left field" choice as writer.
But...as long as DC keep present policy of involving Superman in endless cross-overs and allowing several writers have a go at writing him in his various comics we're going to continue getting a load of average..or poor-ish...stories. Get somebody in sole charge...either a visionary editor or a top quality writer.