I bought a pair of QC2's when they came out. Got a free replacement a couple of years later when the headband had problems. But the case too up too much room in my carry on.

Then I bought a pair of custom Ultimate Ears -- no noise canceling but the ultimate in isolation. So much, I stopped wearing them when riding the local bus -- I'd get so into the music I'd miss my stop

But they had issues when traveling. I couldn't hear announcements or the FA's -- at because they twist into your ear cancel it takes a few seconds to get them out.

When the QC-20s came out I bought a pair -- they were decent but I never could get a good fit (spoiled by the UEs I guess).

After reading this thread (and others) I sprang for a pair of the QC-25s before my last TATL trip. The only ones I could get on sort notice were the white ones -- at least I don't look like all the Bose wearers on the plane

After the two flights (plus a bunch of train rides in Europe) I am pretty happy with them. I'm not sure the case takes any less cubic space but the shape fits better in my carry on and I was able to wear them for a long time without discomfort. I also used them on a couple of Skype calls and they worked perfectly.