Bose QC3, left in seat pocket of a plane we boarded and then deplaned. A heavy wheelchair broke the cargo door seal while they were loading it. I realized they were missing while on the plane they switched us to, before takeoff. Called United, they couldn't reach anyone at the other gate to look for it. Filled out a missing item report when I landed, but never got anything back. Annoying, since that plane was definitely moved and repaired before any other passengers got on it.
Replaced them with AudioTechnica ATH-ANC3s and have been very happy with them, especially the much smaller size (and price) compared to the QC3s.