I've been chasing high end headphone sound for about eight years, and in that time have owned dozens of headphones, from the best budget on up. FWIW, I have a large head and have also struggled to get some headphones to fit well.
I ended up becoming a true fan (fanboy) of ZMF headphones. I currently own three and owned at least another 4 or 5. I gravitated to ZMF because their "house sound" suits me so well (slightly warm, definitely musical, great bass). I need open back headphones due to migraines & tinnitus; my current favorites are the Verite Open and Caldera Open. They both fit extremely well.
I can also highly recommend ZMF's least expensive headphone, the Bokeh closed. If a closed headphone suits you, these are quite large, very comfortable, and ZMF's steel inner headband can readily be bent to adjust clamping force.
Another headphone I can recommend based on superb comfort is the original Meze Empyrean. The sound is lovely: not the highest resolution around, but very spacious and ear friendly planar sound--and the comfort is simply beyond reproach. You can sometimes find these on the used market. I used HiFiShark.com to track used gear.
If you get any of these headphones, you'll get better sound from a desktop headphone amp. I'm a true addict/hoarder of amps and can advise you on that if you feel like contacting me (don't want to hijack this thread).