Definitely the case quality and the fact that it serves as a supplemental charger, even when not connected to a power supply. Wireless charging along with lightning charging as well as super audio quality that is indistinguishable from wired headphones of a similar form factor and price.. that's why AirPods win.

The pairing part is just a one-time thing and yes, the experience is nice, but pairing ease isn't the primary selling point. My portable Bose speaker paired almost as quickly as AirPods.

Criticism of AirPods is almost universally from people who've never used the product.