ChipFlip
Here's a comparison that shouldn't work and sort of does: the Sony WH-1000XM6 at $496.71 used against the Beyerdynamic T1 at $530.16. One is the current benchmark for noise cancelling. The other is a semi-open audiophile headphone from a company that doesn't chase trends. Same rough money, almost nothing else in common.
The XM6 wins everywhere convenience matters
Active noise cancelling that genuinely works, wireless, multipoint pairing, a battery that lasts a working week, and a control app that lets you reshape the tuning. On a plane, in an office, or walking around a city, nothing in this comparison is close.
Sony also tunes these to sound pleasant rather than accurate, which most people prefer and some people find frustrating.
The T1 is a different category wearing the same price tag
Semi-open, wired, and built to a standard of fit and finish that used headphones from this tier tend to hold onto. Soundstage and instrument separation are where it pulls decisively ahead, and once you've heard the difference on a good recording it's hard to unhear.
It also needs an amp, leaks sound in both directions, and does nothing at all on a commute. This is a sit-down-and-listen headphone.
Battery life is the hidden asymmetry
A wired headphone from 2010 still works. A wireless one from 2010 mostly doesn't, because the battery is a consumable and replacing it in a sealed cup is somewhere between difficult and impossible.
Buying the XM6 used means buying someone else's battery cycles. Ask about age and usage before committing, and factor that the useful life is finite in a way the T1's isn't.
Bottom line
Buy the XM6 if this headphone leaves the house or shares a room with other people, and accept the battery as a wear item. Buy the T1 if it lives at a desk with an amplifier and you care more about how a recording sounds than about silence around you.