The only failures I've seen with an AK are because of promags (failing to feed, and double feeding).
Never heard anything good about their polymer mags, but I haven't heard much of anything about their steel mags.
And if I recall correctly, promag actually manufactures Tapco's mags. What that means, I couldn't tell you, but I have a bunch of Tapco's AK mags and they work fine for range use.