CProducts magazines are iffy at best and the company is run by a nitwit. I have had nothing but problems with the 5.56 and 9mm AR mags I've bought from them. They must have monkeys making the magazines over there, 'cause I know a monkey is in charge.
Camenga Easymags are a solution looking for a problem. Get one of
these and don't look back.
HK mags have proven not to be the godsend that everyone thought they were. Among other things, the fact that they are from HK screws them up pretty royally. You CANNOT get spare parts from HK. Spring goes bad? chuck it. Follower problems? chuck it. In addition they have proven not to be the uber-reliable solution that they were expected to be. Many people that are actually issued the damn things ditch them for other options.
GI mags were, are, and will be more than sufficient. I prefer to get mine from
Bravo Company USA which sells the D&H magazines with their own floorplates. If you buy in lots of 100 (get a few friends to go in with you) they can be had for $10/ea with the green followers or $11 with the Magpul anti-tilt followers. Best deal going anywhere.
As to the Pmags, I like them just fine. I find the debate over them somewhat humorous, as most of the detractors refer to "the kool aid" which is usually a sign to me that it's time to put that person on ignore if the forum has that feature. Those that lack facts and knowledge resort to cliches, and interweb cliches like "drink the kool aid" are the worst.
I have 11 Pmags and like several things about them. As mentioned above, the effort required to strip a round out of the magazine is much less than an aluminum or stainless magazine. Also, you can load 30 rounds and still reliably seat the magazine on a closed bolt. The wide floor plate also makes a good gripping surface for certain kinds of reloads.