I work in a cube farm can get loud at times. I listen to music to drown out the noise but my ears can only take so much loud music before I have to give up and put up with the noise around me. I looked into isolating headphones and I've found that Shure makes the best in the business as long as price doesn't matter.
The only downside to Shure, other than price, is the sheer number of models they have. Shure's entry level earphone is the E2. Following the E2 are the E3, E3C, E4, E4C, E4C-N, and the $500 e5. The Shure website lists the difference in price but not the features or the reason for the different price.
Its taken me weeks but here is the breakdown. The E2 will sound better than anything you've ever used before but there is still room to grow. The E3* series is the price to performance sweet spot. The E4* is a noticeable step up from the E3* without breaking the bank. The E5* is the best on the market but you pay a premium for it. If you have the cash to spend the E5 is worth every nickel (all 10,000 of them).
The C or the C-N doesn't change the technology or form factor. The only difference in the different options seems to be color and cord length. There is a G option on some of the earphones that may offer a sound stage ability which will allow the source of a sound to move forward, back, left, and right instead of just existing between you ears.
I'm still not sold on spending that much money on earphones, but the reviews do make them very tempting. Perhaps in a month or so I'll learn what they sound like in person.