I have played with both and after the last match I'm going back to AI Mags at matches. The pmags are fine for range trips but if you're out all day in the elements the PMAGs don't hold up as well. The nice thing is you can take them apart and clean them. The downside is a dusty environment gums them up quickly.
AI Mags have never let me down, wet/dry/warm/cold/dusty/rainy/etc they keep on working.