If comfort is a main consideration, you may prefer a circumaural portable, like the UE6000, the DT250, or the Ortofon O-one, to an on-ear headphone, like the Onkyo you reviewed here and the M-80.

Well the problem I have with that Marco is that firstly, I'm a glasses wearer and have always found circumaurals incredibly annoying with them. That's not a problem for my desktop setup as I'm shortsighted so I can see my computer monitor just fine, but while I'm out and about I need my specs. And secondly, I just don't consider circumaurals small enough to be portable. They're just too big, and the vast majority of them have no folding mechanism. I certainly have no hope of storing them in my pocket when I'm done, which only leaves my neck, and they're too intrusively large for that either. 'Portable' and 'circumaural' just are not all synonymous in my eyes (or on my head).

Possibly the HD25's, the Momentum On-Ears, or the new DT1350s?
 
Quite honestly the Sennheiser HD238 is very comfortable and a great set of cans for the money...seems like you can typically find them for $60ish.  Slightly more balanced than the M80s (but still fun)...a little less bass and better mids/highs.