I would recommend Solitude XCS.
I did lots of research before ordering these. I'm glad I did.
Btw, I first found them at
http://www.headphonesunboxed.com/best-noise-cancelling-headphones-under-100/ (in case you'd like to see how they look like).
First off - noise cancelling works, and works well. It doesn't do much in the voice frequency range, but as for the low repetitive frequency of an airplane, or the loud HVAC system in my lab at work - it simply disappears.
They are comfortable. These are an over-the-ear design so your ears may need to breathe from time to time. I will be wearing them for the majority a very long overseas flight to Asia, and I can't imagine any issue sleeping with them on.
The plug is removable ear cup which is key for storage, reliability, and convenience of moving around in-flight without a cord to manage.
The sound does cut the low end somewhat with NC enabled, as expected. The sound quality is good - the highs are crisp - so it is clear that the driver has high dynamic range. With NC off, the sound fills out in the low end. In amp mode, the lows are boosted and I suppose that would be ideal for some genres. I mostly listen to rock - but I'm happy with the way they sound, fit, and cancel noise.
I've tried a $50 sony pair that did nothing. I also have tried the Bose QC's which may have done more in the voice range than these as far as NC goes (it was a long time ago). But I certainly couldn't imagine paying $200 more for those.
Excellent value. 100% recommended.