I second the Beyerdynamics DT770 if you love bass. If you want something more balanced and musical get AT A900s. I absolutely love Audio Technicas. Personally own A900s and their W5000s w/AT-HA5000 amp.
I wouldn't describe the A900s as musical at all. I found the midrange to be lifeless and fairly boring (an above poster called it "distant"). I owned the A500s for a short period as well and would say that the midrange is fairly similar. They are definitely one of the more comfortable cans if you can stand the pleather pads.
You might also consider the AKG K240, but they are harder to drive than the DT770s and A900s.