For the past several years I have probably spent more time with earphones on than off. I have read all I could on earphones, listened and owned a variety of earphones and have concluded that the more you spend on earphones, the better they sound. Most reviews I have read concentrate on the quality of the sound, but I contend that in the real world there are other factors to consider in determining which earphones are best for you.
1) Some people are just not comfortable with earphones or in canal earphones in their ears. It makes sense to try them on at the store or start off with an inexpensive model to see how well they wear on you.
2) Your listening source may determine what earphones are best for you. I mostly listen to spoken word broadcasts and recordings, for which you don't need great earphones to understand and enjoy the programs.
3) If your sound source is not that good, good earphones may emphasize the shortcomings of the source.
4) Some earphones are more convenient than others to wear.
5) While a great advantage of earphones is their portability, the more you take them out, the more you subject them to possible damage or loss.
For years I used a Radio Shack pocket radios and Radio Shack earbuds with in line volume control to listen to spoken word broadcasts. I found that I could lessen the static hiss by turning up the volume from the source and turning down the in line volume.
I then migrated to the Sony earbuds, currently using the MDR EX51LP. I initially thought they were worse than the Radio Shack earphones until I figured out how to use the right sleeves to achieve a good fit in my ears. I also started using the MP3 players with radios. The quality of the music and radio signal on the MP3 players was good enough so that there was little need for an in line volume control.
I like the Sony earbuds for their behind the neck style which allows one to just remove the earbuds and let them drape over your shoulders. They use a lighter wire which is more comfortable than the Shure earphones, but not as durable.
Shopping at Fry's Electronics, I came across and purchased the Sony E3c earphones. I was very pleased with their performance. In a later visit to Fry's, and in what may have been an impulse purchase, I got the Sony E5c's. I figured I could return the E5cs if they did not live up to their high price tag. Both of those earphones are great, and I no longer have buyer's remorse about the E5c. When I want the best listening experience, I put on the E5cs, and my appreciation of them has only grown since I purchased them. Even when listening to spoken word, both the E3cs or the E5cs put me in the same room with the broadcaster. And music, well it really does take on an extra dimension. The E5c's have a lower, more satisfying range than the E3c's, and a very precise definition of the bass.
I paid $40 for the Sonys, $175 for the E3c's and $500 for the E5c's. Is the sound experience worth the price difference? Looking at prices written on a piece of paper, I have to admit that there is no way that the sound of the E5c's is ten times better than the Sonys. But I am so glad that I have them.
However, my main earphones are the Sonys. They sound good, and when fitted right, they have a low end that I think many listeners will find satisfying. They are more convenient to wear, removing them from your ears and allowing them to drape on your shoulders is more convenient than removing the Shures. The Sonys have less sound isolation, which I contend is more practical than the than the greater sound isolation of the Shures. You can hear more ambient sounds when jogging or biking or driving and people around you can communicate with you. When wearing a wool cap or other headgear, the Sonys are more comfortable and less likely to become dislodged. Losing or damaging them involves less of a financial loss - I rarely take the E5cs out or on travels.
I am looking forward to advances in earphones and will be looking for where future products place on the quality/price scale. I also hope that local retailers will begin to stock all of the earphones that are reviewed so that I can listen to them myself. If I had a chance to try on the Etymotics or Westones or Koss's, I may well have purchased them instead.