FWIW, my vote is for Clarity Aloft. A lot cheaper than Bose-X, though still clearly a luxurious choice at a bit over £300. They're in-ear types, passive but with phenomenal isolation, they weigh almost nothing, and they're so comfortable that I forget I'm wearing them until I turn the master off after shutdown, and realise the instructor's lips are moving but I can't hear anything.
I got mine just after I started circuits, and the difference it made was phenomenal - RT just seemed so much easier, substantially improving my brain overload management and thereby actually making flying easier.