There's a pretty good big article about it here.
https://www.andrewmunsell.com/blog/f...wireless-power
Basically most of android has settled on Qi (meaning Google Nexus devices, LG, Motorola, and Sammy), but Samsung said it would support both standards beginning with the S4.
To make things even more confusing AT&T has officially announced it would support PMA so if you buy a wireless charging back directly from AT&T it will be PMA but look EXACTLY the same as the Qi. So shop carefully.
I didn't realize it but AT&T had announced the PMA back earlier this month.