This brain tuning to a sound is imo the decisive effect for most people when it comes to comparing headphones. I notice it a lot as i have some pretty different sounding headphones.Looking back through this thread there are some interesting comments on how your ears become accustomed to the headphones you listen to predominantly. I noticed this myself when I tried my friends wired, open back headphones the other day which are objectively superior and much more expensive than my PX8. I just didn't like the sound of them but I wonder how much of this is that my ears are now tuned into my PX8s and so my brain is just rejecting a different style of sound. Maybe this is less of an issue fir you guys who seem to have every model going in your ownership and so vary it up more.
The B&W sound is very 'thick' for lack of a better phrase, so when jumping to something like a Focal Clear or 560s those headphones can feel empty or a bit thin in comparison, and then you attune and see their strengths.
Peronally I don't think closed back headphones compete well with open, for my tastes. I'd easily take a 560s over a PX8/Bathys and it's a 160 dollar headphone. But alas, we can't get that sound on the go!