i still have the Logitech G35's, they went a little quirky after a while, great to use, but they started to drop and clip audio during games and then developed a noticeable whine in one speaker, which for USB headphones, is a glaring problem, since all the conversion from usb to audio happens in the headphones.
sennheiser, bose, koss, shure and grado's are super expensive here in Australia, the prices jump from $150 to $250+ if you want something decent, while the price on amazon stays near $90 for both (sigh). so, it's key to do the research. for all of these, did the research on head-fi, (which is more like an advanced course in reading between the lines.)
currently, i have the brainwavz HM5, cheap $110 ish closed heaphones, with a mod-mic attached, a $20 boom microphone with a magnetic clip. i mostly use these for gaming and working at night. i found these through gaming forums, who also recommended the ATH-M50s and a dozen others, like the V-Moda's, etc. and because i had the G35's before, i later bought a sound card for my home PC, the asus xonar essence STX, which has an audio amp for headphones.
also have beyerdynamic DT990's i got cheap off ebay ($250), replacing some older plushy Beyerdynamic DT531's that need new wiring (i think i pulled the speaker wire out on one ear, but it could be the plug, idk.)
I thought about the Audiotechnica ATH-D900's or the ATH-M50, they've been suggested a few times, but i prefer the portable earphones most times.
I have the etymotic er6is, and shure SE115+ for the iphone headset, and, on the high end, i have the Head-Fi RE-Zero's, which seem to work really well compared to everything above for $100. i've broken like 8 earphones just through putting them in a pocket, including some really expensive ($500) ones, 4 pair of UE's, and some cheap sony ones.
i've bought headphones without doing all the hours of [strike]senseless debate[/strike]research, and they just plain snapped after a few months of use.