This one. I have it and it is a 1 for 1 of the G19. Weight and feel are dead on and it even breaks down like an authentic unit. I would dare to say that aftermarket sights would fit on it as well. Full metal slide, CO2 cartridge is in the magazine, full blowback... I use it for training. Fits my G19 holsters.
Way back when, folks made Glock Airsoft replicas until Glock shut that down. There are still a few out there, but most are like the Timberwolf and are modified versions.
I just got my GBB G19 in from Rainbow 8 the other day. I ordered 2 extra mags with it. I've been plinking targets all weekend in the back yard. Makes EDC draw practice easier and cheaper. Has functioned flawlessly.
Just received a Umarex Glock 19 BB pistol. I haven't shot it yet but I am slightly disappointed it doesn't fit my kydex G19 holsters, too tight in the rail area.