The best all around carry and defensive main or ccw weapon available, in my strict opinion. The only handguns to come close are the xdm and the cz compact. It is my strict opinion that this is a handgun that will fit every need for the average through advanced shooter. I have seen very little difference in accuracy between this and the 17, as magazines are useable from the 17 to the 19, and the fact that it has been the most reliably consistent handgun on the market for decades now.
I firmly believe that if you have only one handgun, it should be the glock 19, it is reliable to a fault, extremely simple to use and can be concealed and shot by virtually anyone with a modicum of skill generating solid hits.
I use gold dot 115 grn or 124 grn and the hornady critical DUTY 135 grain not + or ++p. Highly recommended, absolutely for new shooters because it is virtually idiot proof. It is drop safe, I have personally dropped it loaded over 10 feet on to a variety of surfaces and have never, not once had it fire on its own.
I prefer the Generation 3 as well, regardless.
Test carry ammo at least 200 rounds minimum, one failure, in 200 rounds is too many. I have never had a failure to fire, chamber or work properly in the ammunition mentioned.
I have taken wild hogs/javelina with the glock 19 and put them down with one shot using these rounds, once even penetrating the skull of a russian feral boar. Dropped instantly with that one.
Always it is your choice, however, in my experience (100s of thousands of rounds through 7 different glock 19s over the last three years.)
I use XS big dots or dawson precision black on black talls (for use with supressor) youll want a booster, wolf barrels are least expensive aftermarket and offer very solid accuracy. Storm lake and others make wonderful barrels as well.
After sighting it in, you can hit targets out through 200 yards easily, yes I said easily! 50 yards you can keep rounds within 12″ and have adequate power to stop unarmored targets. Grip TIGHTLY, DONT LIMP WRIST EVER!
Use an attached light again your choice, my personal choice is the tlr3 by streamlight, small but bright and very reliable!
Your choice, but always test, always.