I like the McCormick Power mags and feel the most comfort with their reliability. I load 8 and chamber one, leaving 7 in the mag. Superstition maybe, but over the decades of shooting many types of magazine fed firearms, I've come to suspect (imagine?) that maxing out a mag's capacity seems to increase the chance of issues.
I strip and clean new mags and used mags, springs and followers, using Ballistol, wipe dry and rub everything down with a thin but well rubbed in coat of Mil-com. Don't know if this is the reason, but I very rarely have any mag issues.
That said, well cleaned or not, I've never had any issues with magazines that came with a firearm from reputable manufacturers. Nor have I ever had a problem caused by plastic followers.
But, ca 2015-ish (?), I bought a 2 pack of 1911 mags at a LGS, made by a well regarded manufacturer, that had out of spec mag catch/release notches. Inserted, they had a lot of vertices play. I called the manufacture. They asked me to send the mags back. I did so, and a couple weeks later, I received 6! new mags and a nice note of apology, acknowledging the defects, etc. Those 6 mags have worked perfectly ever since.
My 2 cts.