I have to be honest... I'm an AKG guy. I love their headphones since a decade or so. I did try Sennheiser, Audio Technica and other "classic" but always came back to AKG. It might be ear-dependent : I spent a lot of time listening to various style and mixing with the MKII series. Maybe my ears have got used to ? Plus, as a bass player, I don't expect bass / sub frequencies to be super pumped but "at the right place" and those headphones don't fail to kick them in the mix where they belong. It's all about BALANCE. Take that Bose and Beats.
The only reason I bought a new one is because of the the previous generation of "headset" (or headband, whatever you call it) : it used to be stiffer so it cracked here and there before splitting in two after 5 years of intensive use. The new headset is softer and looked like it'll last longer.
The only downfall : the output impedance doesn't match the industry standard. That's where Sennheiser models shine brighter. It's a bit frustrating because it sounds like AKG headphones fail to show their full potential.
So turn the knobs up to 11 and don't forget those precious Lemmy's words of wisdom : if it's too loud, you're too old !