Easy recommendation: ATC sealed/acoustic suspension 2-ways. You could get the SCM12 Pros new for <$2K; or the SCM19 or SCM20 passives on a used basis.
I own the SCM12 Pros. The sound is mindblowingly good: assertive, detailed, dynamic beyond belief, yet musical and truthful, not tiring/edgy. ATC all the way!
PS: I second the recommendation of buying something from The Music Room (www.tmraudio.com), I bought an expensive pair of high-end headphones from them, and it was a painless, ideal transaction.
Note: @perkadin stated the URL as "trmaudio.com," which doesn't work & leads to malware alerts