Sennheiser for life, though I am looking to try out some Grado's, particularly the sr60 which is also proclaimed to be a true classic, sub $100. The Grado is open air though, versus the closed design of the HD280pro. The HD280 is spectacular, but after going open air with the Senn HD595, i've had trouble accustoming myself back to the closed nature of the HD280pro. But it has its uses, airplanes, noisy public areas.. I'd never bother with the 595s in a place like that.
There's no denying though that the HD280pro is an excellent gateway choice into the world of top notch headphones.