Probably varies quite a lot by person:
Sennheiser HD6XX has an utterly unbearable clamp force. Most uncomfortable headphones I’ve ever used.
Focal Elex (should be similar to Clear and Stelia?? Also very uncomfortable. Too much clamp force on the upper jaw area.
For me by far the most comfortable headphone I own or have used is the Sony MDR-Z7R2. Can listen for hours in comfort. Sound pretty good too.