If you are looking for a noise cancelling headphone, the Bose QuietComfort 20i is your top choice. After you bought yours, I am sure you want to experiment with the different sized ear tips -- and that is when the trouble starts.
The Bose ear tips attach to the headphone in a very different way than all other earbuds style headphones that I used. Instead of just snapping onto the earbuds over some sort of ridge, there are two additional little plastic wings/tags that the ear tips must fit over. If you are not careful, you will break them when you try to remove the ear tips.
To help you not break them, here are some close up pictures of those wings/tabs. Study their locations. Also watch this video instruction by Bose. Then carefully remove and replace the ear tips as instructed.