If money were no object, all were readily available, and weight was not a concern, I would probably buy in this order:
Circle 10 polymer waffle mags
Surplus steel in very good / like new condition (Chinese or Eastern European)
Toth Tool polymer waffle mags (still a little untested)
Bulgarian commercial steel
Magpul M3 (I've heard complaints about them but have not had any issues myself)
Bulgarian commercial reinforced polymer
I like the reliability and durability of the Circle 10 polymer mags, but they are expensive, heavy, and bulky.
A couple novelty mags that are great but expensive and hard to come by:
Surplus Russian bakelite
Hungarian 20-round "tanker" mags
Based on availability these days, I'd probably look for Bulgarian commercial steel, Magpul M3s, and Bulgarian commercial reinforced polymer mags. Surplus mags still seem to show up at What A Country and a couple other places, but they're getting expensive and hard to find. Prior to the pandemic, surplus steel mags were already rare to find at shows, compared to a few years ago.