I agree that with many that it is a very subjective matter, some people would prefer accurate details, imaging position etc. some would prefer realism, timbre, layering etc.
In short, there's plenty of available products in the market for you to demo, with plenty of reviews (do take them with a pinch of salt) for you to take into account, there's not one absolute best headphone.
Personally, I really like Audeze LCD-2s, with their lush and full-bodied sound; however, I do admit that they have their issues such as the clamping force and weight. The Sennheiser HD650s are another good pair of headphones, with great sound and comfort. Admittedly, I'm less experienced with headphones, and it would be a whole new adventure when I step into buying a pair after my National Service.
P.S. I saw "iSennheiser" on VR selling a Beyerdynamic Custom One Pro, I wonder if this is his/her base of comparison?