I've only seen good things written about the m-stage, so it's obviously a good choice as well.
I can only buy online (I live in the middle of nowhere), and the E9 is my first dedicated HP amp, so I can't compare it to any other HP amps (other than the cheap tube amp, which is pretty much appalling in comparison - lots of hum, distortion and channel imbalance - but it needs tweaking anyway), so I'm just repeating what others have said.
That said, I'm very happy with the E7/E9 combo and consider it excellent value for money.