With a Steel framed 1911 I like Chip McCormick PowerMags.
I find that a mag with an extra power spring like a CMC PowerMag is more reliable in most pistols. For an aluminum frame pistol an anti-tilt follower is very important. Otherwise the follower can move forward and nick the soft aluminum feedramp.But, what about someone who has a choice of just about any mag, because they all work? What sort of design features are preferable?