I have NIW FN Belgian mags, DSA "Good" grade Steyr mags, gun show "U pick-em" grade Steyr mags, some aluminum mags, and a 10 round DSA benchrest mag. Of all of them, the 10 round mag sees the most use.
The NIW ones are just too nice to unwrap and use when the used ones are so readily available and work so well.
The aluminum ones work fine and it's easy to feel the weight difference in loaded mags. I can't say how well they'll hold up over time compared to steel. The lip on the front that engages the mag release is the part I'd worry about.
The DSA used mags have been the most consistently good quality ones for me. All the used ones needed a good cleaning to remove cosmoline, grease, sand, gunk, etc.
DSA sells 20 round mag springs for $1.00/ea in quantity. These go a long way toward making the used mags work like new ones. That reminds me - need to stock up on some more while the getting is good.
Mag pouches are tougher to come by. Tapco used to sell good quality 2 mag South African canvas pouches but I don't think they have them anymore. I haven't tried the other suggestions offered on this thread.
Welcome to the FAL fraternity!