For almost as long as I've been making transatlantic flights I've depending on Etymotic in-ear monitors. The last couple years it's been a pair of HF5's. My only problem is after 2-3 hours my ear canals just can't take it any more (to be precise, my left ear canal which is oddly shaped and very curved).
So for this year's trip I'm adding an over-the-ear noise canceling headset. It's one I picked up in Like New condition from Amazon Warehouse Sales for 60-something dollars. Audio-Technica ANC7B which is an older (2009-ish?) model that runs on one AAA battery and has a wired connection to your phone or music player.
From trying it out at home, the downside is going to be it is very hot, and very tight on my ears. I think 90 minutes without taking a breather would seem very long. But it is pretty effective at blocking all sound even before engaging the noise-cancelling and once I flip the switch to ON any low-mid frequency sounds are almost completely knocked out.
Pretty darned effective, never tried a Bose set so I don't know it compares to the pricey ones. Sound quality is more muffled than harsh so not really objectionable but it won't replace my Etymotics for extended music-listening use. I'm envisioning wearing the HF5's and listening to music to start the flight, pulling them out when my ears get tired and just using the Audio-Technica to muffle the noise for an hour or so then going back to the IEM for some more music.
Neither ear canal plugs or an over-the-ear headset are something I'd want on for an entire 8-9 hour flight.