I am most happy with AKG $100 dollar variety.  Works good with eyeglasses too and wearing for long periods of time.  What are your favorites?
http://www.amazon.com/AKG...p;keywords=AKG+K142+HD
 
I compared with Sennheiser HD 495 (EOL) and Audio-Technica ATH-M50 http://www.amazon.com/Audio-Technica-ATH-M50-Professional-Monitor-Headphones/dp/B000ULAP4U
The M50's sound best but I like the AKG K142 HD best due to comfort.

Tiamat 7.1 are super comfy to me

ATH-AD900X

I buy senheiser for the comfort. I own pc g4me 360, hd 598 and hd ??? (one below hd 800). Sometimes forget they are on my head. And if you game for hours in a warm environment, the openness of them really cools the ears.

The headphones woot sent me on accident " Razer Carcharias " where surprising light and comfortable for me.

My Yamaha Pro 500 with extra padding (otherwise it hurts me it but with the extra padding it's a great fit).

Well, the differences generally have to do with the amount of power that needs to go into the headphones.  If there's insufficient power, then the volume will be really low, and the sound quality will be rather dull.  The lower the value, like 250ohm, the less power needed to drive it.  The highest you usually see is 600ohm.  It largely just depends on which headphone you're looking at; most of the regular or popular heaphones run off 32ohm.  Most soundcards can support up to 600ohms, and the headphone port on some onboard audio ports for the motherboard can support up to 600ohm headphones, as well.  However, I've found that those are still generally insufficient and an amp in addition to the motherboard or sound card will be needed to really pull out the sound.
 
The DT-880's are a great case to point out something.  People have varying degrees of how much they like the headphones at different levels of resistance.  For people who've tested the 600ohm version of the headphones with sufficient power to drive them, they really like them.  Others prefer the 32ohm version whether or not they have sufficient power.  250ohm's of these are still fairly easy to drive, but if I remember correctly, people tended to prefer either the 32ohm's or the 600ohm's more than the 250's.  However, you should look that up again on somewhere like Head-Fi to confirm.  Some of that is a subjective perception, of course, but if you go with a 600ohm headphone variant without the power to properly drive them, then you're not going to be as happy with the sound.  
 
If you're using equipment that can amp the amount of power going to the headphones or a sound card that supports up to 600ohm, then the 32ohm or 250ohm variants will sound pretty nice.  If you have an amp that can drive the 600ohm versions, those will be better.  Cell phones or MP3 players generally sound better with 32ohm headphones, as they need much less power to drive.
 
I got the 600ohm version to go with my Auzentech HomeTheater HD card (don't bother going to Auzentech's website; they're now defunct and the site appears to have malware; just go somewhere else if you want to look that up).  They sounded great to me at the time, as they were the best headphones I'd owned.  However, I didn't realize that the 600ohm claims of the HTHD card just wasn't enough for them.  I got a Fiio E9 desktop amp, and the sound immensely improved.  The E9 (now the E09K) really changed what I expected out of the headphones.  No, it's not the kind of amp they really need, but I can't really afford those kinds of amps, lol.