I picked the m3's up having previously been an owner of the m2's. The sound quality is noticeably better. They fit better on my (large) ears and the headband is more comfortable than the old pair.
I use these when I am out and about (obviously) and at work for listening on my LG V30 using the Sony LDAC bluetooth codec on Oreo. Also heavy use for conference calls via bluetooth on my macbook. Call quality on the conference calls is good. about 16,000mhz in and out.
The headphones are lighter, sleeker looking and just about perfect in all categories. Not comparing them with my high end desktop/home headphones of course but they aren't actually that far off. USB C is a nice touch too. Same cable as my V30.
Anybody got any questions, shoot!!