Perhaps a pair of NVX XPT 100 would be a nice match. You can pick up a pair for $90 shipped.
They have a neutral tuning and work well for a variety of genres, built well, and are comfortable to boot. For a closed back headphone they have a wide sound stage (ability to perceive depth in audio) which is good for immersion. The ATH Mxx series from Audio Technica are known to have a small soundstage and personally I would avoid them. They are not the most comfortable either. I have owned the m50 in the past and would not recommend them for gaming since there are better options out there for around the same price.The m40x seems to be similar in sound and build, though it has smaller drivers leaning towards the neutral side where as the m50 was v shaped in sound (boosted lows and highs with recessed mid range).
Keanex over at head-fi has wrote a detailed review on the XPT100:
http://www.head-fi.org/t/624729/review-nvx-xpt100-a-direct-brainwavz-hm5-competitor
Video review by Zeos Pantera (headphone reviewer with a sense of humor
)
[video="https://www.youtube.com/watch?v=J2G9qk7IOEA"][/video]
Another option would be the Audio Technica ATH A900x. They go for around $120-$150. It has a wing style headband which is either a hit or a miss. If you have a small head they might slide down your ears since the clamp is quite light. There are mods to tighten the clamp (google ATH A900x rubber band mod). Sound wise they are also neutral/balanced. They have a lush sound with great mids and highs which is key for those genres. Good soundstage as well. Personally I think you would like them more than the XPT100 and would be worth stretching the budget for.
Review by Bagheera @headfi:
http://www.head-fi.org/products/audio-technica-ath-a900x-art-monitor-headphones-japan-import/reviews/8433
Video review by metal571 (also has a review on the XPT 100 if you want a different perspective):
[video="https://www.youtube.com/watch?v=cH_v4SCsChk"][/video]
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Ideally you would want an open back headphone unless you need a closed back pair for low sound leakage and isolation.