Personally I find comfort very important in headphones. Especially if the intended use is gaming. Uncomfortable headphones is a dealbraker in every sence of the word.
For best comfort i like velour earpads and open backed headphones.
I like the Sennheiser HD5XX series with velour eadpads. HD558, HD598, HD595 or my personal favorite HD555 (out of production, but can be picked up on the cheap from ebay). Sennheiser Game One is from my understanding based on the HD5XX series and could be worth a listen. It includes a noise cancelling microphone. Wireless is also very nice, but sadly very expensive. I think Sennheiser RS185 is a good choice because it is open and has velour earpads.
If you are surrounded by a noisy environment I would recommend closed back headphones. Open backed headphones provides better airflow and is less humid, but does not isolate environment sound as good as closed back headphones. I personally like Bose AE2 line. It is very light and comfortable. These are sadly no longer in production either, but can be picked up on the cheap from ebay. Bose SoundTrue 2 have replaced AE2 in the Bose lineup. I have not testet the SoundTrue 2 but my guess is that it is very similar to AE2 and a very good headphone.
I do not recommend wireless that use Bluetooth at home. For travel its fine, but I find it way to prone to bugs for use at home.
If you cant hear distortion, hissing or other sound artifacts when headphones are plugged in to the onboard sound solution on your motherboard, with volume on the level you would have it when gaming or playing music, chances are that the onboard DAC and amp is good enough. The truth is that most onboard audio solutions is as good as it needs to be. External DACs and amps might provide more features, but no significant improvement in sound quality. External Amp and DACs is in my view redundant.
http://www.tomshardware.com/reviews/high-end-pc-audio,3733-19.html
If you listen to a lot of music that is highly compressed I recommend headphones with elevated bass-response. It helps cover up compression artefacts by masking. Sennheiser is generally more flat. Bose usually have a elevated bass.
Recent studies from Harman, Phillips and NAD, seems to indicate that flat frequency response is perceived as treble heavvy and bass-light. Slightly elevated bass is perceived as neutral.
http://seanolive.blogspot.no/
For the serious audio nerd i recommend subscribing to Audio Engineering Society:
http://www.aes.org/
It is dry reading compared to Head-Fi and the likes, but much less snake-oil. Serious studies are scrutinised before publishing. Findings hold more merits as the methods are explained in detail so you can make up your own mind if there are weak-points in the process leading up to the findings.
Good luck.
Edit: one more thing. Mass-produced headphones like Bose AE2 and HD5XX have good support and affordable replacement earpads and headband. Original parts are more expensive, but there are some good china parts. Some are good quality and dirt cheap. Have worn out a couple of earpads on my HD555 and AE2. After replacement parts the headphones are as good as new, and will last many more years.