I find open cans to be more comfortable than closed cans, as open cans have better airflow to keep your head and ears cooler. I have listened pretty extensively to the Audio Technica ATH-AD700 which is widely considered to feel similar to having pillows on your ears, and also the Sennheiser HD555 (old version). Both models were very comfortable for extended periods of time, with the AD700s feeling looser and softer, and the HD555s being slightly tighter with better noise isolation because of the way the headphone cups around your ear more