Quiet is quite right, but I'll elaborate a bit.
Armalite AR-10 mags are derived from US-made M14 mags and are high quality. BUT... no one sells them except Armalite, and they cost a lot. 10-packs ordered from Armalite's website get you down to $27.50/mag plus shipping, but smaller quantities are painfully expensive.
At least four companies make mags compatible with the DPMS pattern:
DPMS (the worst of the group)
Magpul
C-Products
Knight's Armament
There may be others. CP mags for the .308 are high quality and my #1 choice, even though their 5.56 mags are inconsistent at best. The Magpul .308 Pmag is, IMHO, not as good as their 5.56 Pmag, in particular it doesn't have an anti-tilt follower and tilt can be an issue just loading it. CP mags run $15-18 each for 20 rounders, Pmags are usually $18-19, DPMS are way overpriced at around $30 and I've never attempted to find a Knight's mag.
The Armalite AR-10 mag is, maybe, just ever so slightly more durable than the various DPMS/Knight's pattern .308 mags, but not to an extent that matters.
I think the magazine design is the biggest thing holding Armalite back now. It was a logical decision during the AWB, but 7 years later I think they need to realize that they are Betamax and switch over to VHS, even if it's not any better.