I have a couple different ones including Pierce, Glock OEM, and something unlabeled I don't remember the brand of anymore. The glock works as well as any.
I have some of the longer mags also. I only carry them now as third or fourth reloads. I don't like the grip gap.
I agree. Or a +2 Glock extension for the 19, or use a 17 mag with the +2. I'd personally stay OEM for Glock extensions, no real reason to look elsewhere and you'd be hard pressed to find more reliable ones.
If the G19 is a CCW I don't want a mag extension that could print on my torso, I can't have mag extensions that increase the mag cap past 15 rounds here anyway, so I carry a spare mag & practice tactical mag changes.