I have tried the Bose X, albeit briefly. Personally I don't like the Bose because of it's very poor passive protection qualities. Sure it sounds quiet when the ANR is running, but the frequencies that the ANR doesn't filter and that you don't perceive as being "noisy" will damage your hearing just as much!
I have used the Sennheiser HMEC372, which I found less comfortable than the Bose, but the ANR was equally good and the passive protection is much better. Comfort wise I would say it was on a par with a Peltor. Much cheaper than the Bose.
I have now started using the new Lightspeed Zulu headset and I am very happy with it. It is sufficiently comfortable to wear and the ANR and passive qualities are great. It also comes with some additional features if they are of any interest e.g. bluetooth, MP3 input, etc. Cheaper than the Bose as well.
HTH??