headphones is definitely up for debate/discussion... but the noise cancellation is the best on the market.
If you are primarily purchasing for noise cancellation, and want over-the-ear cans, you can't go wrong with Bose QC 15, QC 25 or QC 35.
Quietcomfort 15s have been around for years and if you can find a reseller that still as them at a reduced cost, the noise cancellation is still very good on these.
Bose's current offering are the QC 25 (wired) and the QC 35s (bluetooth). Both have excellent NC and above-average sound quality. I believe 25s go for $300 and 35s go for $350. Not cheap, but if you fly a lot, they are worth it.