If I buy a Glock magazine, I don’t feel like I got ripped off on the price, and i am pretty much assured that it is going function in the firearm, retain the ammunition when not in the firearm, and not damage the internal parts of the firearm when jammed inside it - even if I’m putting a longer stick into a shorter grip, like when I carry my G26 with a 15, 17, or 19 round spare magazine.
I have had a number of magazines from Sig do other things, after paying ridiculous amounts of money for them. Without a properly functioning OEM magazine, a gun holds absolutely zero interest for me. Perhaps I am labeling a brand unfairly. Do not care at this point. Glock magazines and pistols work. Sig magazines burned me too many times. Done with that.
I would buy HK based on magazine and functional reliability reputation alone, except that Glocks work and don’t cost so much. Still might end up with a USP anyway.