I use the factory +2 mags on my work pistol (G17.5) and have found them reliable and durable. Some of my co workers opt for the Taran or Zev extensions, partly for capacity, partly for the extra purchase when pulling them from flapped pouches on kit, particularly when wearing gloves.
As an aside, does anyone know if Glock is still making the black factory G17 +2 mags? I can only ever find the tan ones when I look online.