One of the best pouches i've owned - Safariland 079 Concealment Magazine Holder, Snap-On, Double - STX Plain Black, Ambidextrous 079-83-41

This is a great mag holster. It's got a strong, rigid, plastic exterior with a leather liner. Mags are held firmly, but remove smoothly and easily. The belt loops unsnap so you can put it on or take it off without removing your belt, and the loops are sized with just enough space between them for a belt loop - so it stays in one place on your belt allowing for consistent draw.

The only down side is that the snaps are extremely tight initially. It takes a few days for them to break-in to allow one-handed fastening.
Pros: Price, simplicity, rugged, stable
Cons: break-in period

This review was written in the old system and had content requirements that are different than reviews written today.