I have owned the Bose Noise QuietComfort I and II for a while now. A few weeks ago (at Macworld) I purchased the Etymotic ER 6 isolator earphones for $99. I seriously love these headphones. I did not get the white ones (ER 6i) because they were designed to compensate for deficiencies in the iPod (from what I understand). These are also deficiencies common in other MP3 players although I don't know which ones.
"6i isolator earphones are designed specifically for use with the Apple iPod and other small portable players, offering 8 dB higher overall sensitivity and slightly more bass than the ER-6 isolator earphones." [link]
I was lucky enough that I could try both the black 6 and the white 6i. The both fit in your ear a bit differently, and I happened to like the black ones better because they use the 2 flange eartip rather than the white 3 flange eartip. Plus they were cheaper. I also tried out the Shure E3c, but liked the ER 6 much better. I also happen to have a great interaction with the people in the Etymotic booth at Macrworld... much better than my experience in the Shure booth. To top things off, the Etymotic people were selling their product in the booth for a nice big discount and they gave me a free Sumajin, which is a genius invention and a must have for all portable music player owners. I like companies that sell their stuff at Macworld... instant gratification + big discount is king
I have yet to get on a plane since purchasing them, but when I do I'll let you know how they fare against the Bose. Scoble says he is going to buy the white ones, but if he doesn't have an iPod I'm not sure why he would. Buzz first pointed to these a few months ago, and of course planted the seed in my head that I must buy them to replace my white Sony Earbud headphones.