I would say my most complete headphone experience so far is with the Hifiman HE400SE, I measured them & also relay my EQ experiences here:
I bought mine brand new in a sale from Amazon themselves (UK) for £69.30 delivered. They came with the same black cable that my Edition XS use. I must say I am delighted with the HE400SE. I actually bought two of them at that price. That was on August 2nd. Amazon were also selling brand new...
www.audiosciencereview.com
They're obviously not in the same tier of headphones as HD800s, and when I say tier I'm referring to price. But the old adage goes that "price is not related to performance". (You can see the other headphones I own that are listed in my sig if you want to get an idea of what headphones I've been exposed to.....and I've done loads of experimentation with EQ over the years.)
EDIT: to me I've found the Oratory measurement for this headphone to be the most accurate out of the headphones I own - in terms of EQ'ing to Harman seems the most neutral & balanced/complete experience. I found something similar with the HE4XX I own, which again is a round cup Hifiman - the Oratory EQ was tonally spot on with that headphone, although it felt like HE4XX lacked overall resolution, but with the HE400SE and my EQ I did to Harman Curve from Oratory's measurement then I have spot on tonality & resolution. I think there's something about the round cup Hifiman's and Oratory's measurement of them that is making them very applicable/reliable to what I view as neutral - it could maybe be low unit to unit variation of these headphones or it could be maybe not much on head variation with this design or something else......just to me it seems Oratory measurements of these have made the most "sense" to me in my experience of EQ'ing all my headphones to Harman. (I do own Anechoic Flat speakers and sub that goes down to 20Hz in room, which has also been Room EQ'd so I think I've got a good sense of what neutral is, albeit it is really quite hard to compare headphones to speakers.)