I'm looking into getting some quality headphones and would like to know what you guys think of the following choices, please try to explain why you made your choice. I'll be mainly using them for Gaming (FPS, RPG) and Music (Hip hop, instrumental, rock, electronic). I'd like there to be some bass, but it's not the deciding factor (don't need my head rumbling, but I want to atleast hear those low notes). Not as concerned with open/close back, just with optimal sound quality. My budget is ~$200, I know some of the choices are in the higher price region but include them for comparison.
Audio Technica AD700 or AD900 or M50
Beyerdynamic DT770 or DT880
AKG K701 or 702
Sennheiser 555 or 595
+1 on the Audio Technica ATH-M50 suggestion. My first higher quality headphone purchase were a pair of IEM's by Head Direct (The RE0's). They received rave reviews, and do sound quite good for their size and price ($80). When I bought my ATH-M50's though, the sound is so nice - easily my preference when listening over headphones. I've had mine for several months - they are very comfortable to wear, have great bass which doesn't overpower, the entire overall sound is detailed and pleasant. I paid $120 for mine and couldn't be happier. They're good at isolating external sounds as well. You'd be hard pressed to find better headphones without spending more than $250.
I've used mine for gaming briefly, they are excellent in that purpose as well. I heard many sounds in L4D that I did not hear over my speakers (And I have relatively nice Logitech Z-5500's hooked up). I listen to Hardstyle which is extremely bass heavy and they sound fantastic playing it, I also listen to jazz, 70's rock, electronica and can honestly say they are very diverse headphones - they play every kind of music I listen to excellently. I have a rather extensive home audio setup, but I must say I really like just putting the ATH-M50's on and letting the tunes flow - listening to the details you may never have heard over speakers. These are the best all around package you're going to get, some of the others you mentioned excel with certain music but don't do so well with others. I'd suggest the M50's for their diversity given you listen to a varying range of music and applications. I do not think you will be disappointed, as I'm rather picky and loved these headphones (I did purchase them based on other reviews as I had no where local to sample them beforehand).