I'll try to keep this short since there are many other reviews that go into great detail. Everyone wants something different out of a pair of headphones, but EVERYONE wants them to sound good and be comfortable. They definitely check both of those boxes for me. I have used the Bose QC's for a long time and here's how they compare in my opinion:- Bose are slightly more comfortable in the headband, but the PXC-550's are so comfortable that it doesn't matter enough to buy them for that reason.- Bose ANC is a little more "complete" but truth be told I don't use it unless I'm traveling, and Sennheiser's is very good as well.- Bose case is better- Bose has a longer distance of connectivity than Sennheiser but I'm rarely if ever going to wander far enough away from my connected device for it to be an issue.- PXC-550 sound quality/diversity is definitely better than Bose in my opinion. I edit audio on the side so my ears are tuned to listen for the little things.- PXC-550 are way "smarter" than the Bose QC and have many more bells and whistles that I personally LOVE, like twist to turn on and off (replaces a bulky power switch) and swipe controls (my favorite thing which I'll get into more later)- PXC-550 has a switch that easily turns ANC on or off which is a must have for me. The BOSE QC headphones have it on all the time by default and if you want to turn it off you have to go through the app which is a pain. I personally don't like listening to music in a fish bowl all of the time, and frankly, it can be downright dangerous if you're out walking the dog or running in the neighborhood or driving a car. I think ANC is good for airplane travel or special situations where external noise is excessive, and that's it. If you like having easy control over ANC then definitely go Sennheiser over Bose.- PXC-550 feel like they're more well made with higher quality materials (speaking of which, the Bose ear cups are much more likely to make your ears sweaty than the Sennheisers so if you plan to wear while being active, keep that in mind.- PXC-550 has a longer battery life (especially when you consider that you can easily turn ANC off when you don't need or want it unlike Bose)So these are just a few of the differences between them and reasons that I chose to buy Sennheiser over Bose QC this time around. As I mentioned before, the addition of swipe controls on the earpiece of the PXC-550 is a real deal maker for me because I'm a Biochemistry research scientist who often spends hours working in a clean environment which means I'm gloved and I can't touch anything with my fingers. So the ability to swipe control (switch track, pause, play, adjust volume, take calls, fast forward or rewind etc) with the back of my gloved knuckle or even a pencil eraser in a pinch is completely life changing for me!! And the controls are VERY intuitive (my 6 year old could learn and memorize the swipes in about 30 seconds) and are sensitive but not so sensitive that I accidentally trigger it. Between that, the sound quality and the easy access to turn ANC off and on is why I went with Sennheiser and I'm SO glad I did! They sound better than any headphones I've ever tried and I've tried a LOT! I cannot recommend these enough. Also, I bought them refurbished and saved some money. I recommend that if they're available too! They came practically like new!Hopefully this is helpful for someone else! And yes I paid full price for these.