I've been getting more and more into headphones for listening to music. Here's a quick hit of some I've tried:
Beyer DT880 - neutral midrange (slightly recessed), light on bass, boosted high treble
Sennheiser HD6xx (same as HD650) - neutral midrange (slightly forward), light on bass, rolled off high treble
Beyer DT770 - moderately scooped midrange, solid bass (not boomy), very boosted high treble
Audio Technica M40x/M50x - scooped/weird midrange, boomy bass, boosted treble
I think the Sennheiser 6xx and Beyer DT880 are both good choices, although it depends if you want a warmer treble (6xx) or boosted treble (880). The 6xx is $200-230 on Drop.com (which is a steal as the HD650 is a $400 headphone) and the 880 is available on Amazon for around $150 all the time.
I'm still tinkering with headphones and would like to try some others to get a compromise between the boosted treble and warm treble. But for guitar, the 6xx is nice and non fatiguing.