Most comfortable headphones

Grado, they range from $80 on up. Light weight. They are all open back so not good for noisy places, just FYI. 

I have found that the Brainwavs leather upgrade pads really increase the comfort of headphones. (totally better than most stock pads).

Other than that, some headphones have a tighter clamp spring which some people complain about.

It depends on what kind of headphones he likes. If Bluetooth, you can look at Sony I have had them for 6 years, and I do not want to change. Along with them, I used wired headphones for the computer, but the wires are constantly getting tangled. And Bluetooth doesn't break as often.

It depends on your friend's requirements for headphones. If he likes headphones, he could choose Sony and Beats. If your friend likes bone conduction headphones, he could choose Naenka and AfterShokz.

OP,

For that money, Audio Technica makes some mean Bluetooth headphones. If your friend doesn’t have/doesn’t want an amp/cd player/DAC etc. and listens to music with a smartphone/laptop, then Bluetooth would be the best option.

Another option could be the Sony WH-1000XM4 noise-cancelling headphones. They sound very good and balanced; unlike many of the celebrity headphones lurking out there.

How comfortable a headphone wears is a personal thing. Over-ear headphones would be more comfortable than on or in-ear monitors.