the audio technica ANC7B are a cheaper alternative to the Bose QC15, though you can't really beat the bose for isolation, they do really well, and nothing really works to beat the QC 15.
if you want something comfortable, the ATH-M50 are okay, the Logitech UE6000, any of the Beyerdynamic DT series, and some of the sennheiser series are good choices.
if you want something closed and isolating, the NVX Audio XPT100 / Brainwavz HM5 are cheap, good monitors. similar price to the ATH-M50, but bulkier and generally pretty good. above $100, there's a lot of more expensive models like the sennheiser and sony MDR/MA models, which would IMO, require some personal experience or testing as they all start to cost $300+ with irregular and hard to discern differences.
if you want something to wear outside, try the UE6000, or an IEM/earphones, a good choice generally are the shure SE215 or Westone 2/3 are very good too.
having bought both the westone 3 and se215 on ebay, (for $80 second hand -- and rinsed all the silicone earpieces in sugar soap to be sure.) they are worn the same way, but the style is very different.
they are a little uncomfortable to get the right fit at first, they are both lightweight and isolate background well, and the cable noise is minimal and tolerable. i have not used the westone 3 or the shure se215 long enough to have an opinion on the quality, they sound good. not too much bass, very unique profiles. i just don't have a lot of music to listen to at the moment without spotify or something else to provide variety.
and on the other end of quality, I also have a pair of brainwavz m5 earphones i got on their christmas special for mobile phone use, the sound is okay, the isolation is casual, i.e. you'll hear street noise, cars, and the like, but not while music is playing. the price was $50 for 2 pairs, and it's a good replacement for the shure pair while walking around, very minimal. very loud at times. kind of interesting since the bass is so harsh, it's unusual to listen to music that has a bass track sound like you're listening to it in a parking lot ampitheater. i can't think of a better way to describe it, there's both too much and not enough, and there's a translation/location effect. anyway. they're cheap.
(i nearly thought about getting the creative aurvana live 2 / UE 6000 / brainwavz HM9 for christmas, but i don't have anywhere to put them, and i still have a lot of non-foldable headphones i don't use that often.)
if you want something specific for price or quality of sound, reddit.com/r/headphones and the head-fi.org forums, are highly speculative and helpful for opinions, e.g. you'll get opinions and a lot of speculation from people who own the headphones/earphones.
on reddit, definitely more suspect speculation than information. but it's generally a good place to check for consensus with other forums about quality. also prices.
