I've recently considered 2 headphones for travel. Though I don't travel too often (about 6 times a year, 2 being longhaul), I really found good use for bluetooth enabled active noise cancelling headphones after realizing how useful they would be on flights. Though 6 times a year may seem like a lot , i'm comparing to people that do in fact travel often.
I recently gotten a hold of the Sony MDR 1000X's and two weeks ago awkwardly tried the QC 35s in a Bose store, here are some strong and weak points in both headphones.
Bose QC 35's
Starting off with Bose, their strong points are in comfort and active noise cancelling. The headphones are a bit lighter (30 grams if I had to guess) than its Sony's 'counterpart'. Though the weight isn't that far apart, the headphones are more comfortable, as I found my ears not even touching the headphones at all. This is partly because the earcups are bigger than the 1000X's and the interior is angled, so your ears wont touch the interior of the headphones. Active noise cancelling is also a strong factor in the 35's, as the noise cancelling does not sound as artificial.
Though this pair of headphones are great, they lack a few of functions. One, you can't turn off the active noise cancelling, but because of how active noise cancelling works, you can partially hear voices. The only thing that muffles someone fairly close to you is the actual seal of the headphones around your ear. Second, the 3 buttons, volume up, volume down and the skip track features are okay, but they lack the backtrack button/ feature, but this shouldn't bother anyone that doesn't use that feature often or at all.
Sony MDR - 1000X's
Sony on the other hand , also has strong points. One being the sound quality and the other being the functionality and features.
First, sound quality. Sound quality is very good all around. All bass, mids and highs shine through. In my opinion the artificial feeling sound quality, added with the minute amount of pressure created inside the headphone boost the bass greatly. I don't know if its just me, but I think this is on purpose, maybe to boost the bass or compensate for the lack of pressure in the sky, as these pair of headphones is very targeted to travelers.
Second, the functionality of these headphones is phenomenal. The only buttons on the outside are the button to turn on ambient sound, with a normal and voice option, a button for noise cancelling, with an option to optimize the noise cancelling if you hold it down, and a power button, which if you press when it is turned on tells you the amount of battery left (low, medium, or high/ full). You're probably asking where is the volume up/ down and skip track button; well that is the special part: Sony has put those functions on the right earcup. To raise the volume, simply swipe up on the earcup, and to lower the volume, swipe down. To pause, tap the center of the right earcup, and to skip a track, swipe forward, and swipe backwards to go back a track. Another cool function of the headphones is that you can put you hand over the right earcup the quiet the music and amplify (slightly) the noises around you, especially voices. This might seem to get annoying as object may be able to mess up your music, but it seems to have a heat sensor or something of the like, so it will only do something if it senses something like a hand.
Both headphones have great sound quality and are very comfortable, but I would chose the Sony MDR 1000X's as the winner, but you should pick the headphones that suit your needs and also based on what is important to you.