On the Gen 1 spent a bunch of money buying all trick parts from all over, Zev ultimate trigger kit with the springs & striker. An aftermarket threaded barrel, aftermarket guide rod & spring, The Slide is the P80 slide they offer, Dawson Precision sights. It's ok but I don't like the old style as compared to the new style and plan on transferring the parts onto a build of a new Gen 2 frame build soon.
The Gen 2 frames are big improvement over the gen 1's both aesthetically and functionally.
I am a Glock armorer so I can buy my upper & lower parts directly from Glock. This actually only saves a small bit of money and takes longer to get orders processed and shipped.
But I have gone to doing that over the aftermarket parts for most of the builds for the most part because I have found most of the aftermarket stuff only looks better than stock but doesn't live up to the hype. You can save time by purchasing upper & lower parts kits already built and you will pay a little more, but the convenience is not a bad trade off imho. One part of the build I WOULD recommend is a Brownells slide. For the money they are very high quality at a really good price when they are on sale. They go on sale with free shipping pretty regularly too. I would NOT recommend the P80 brand slides because they look nice, but their tolerances are inconsistent and not anything close to a stock Glock slide.
View attachment 74481Gen 2 G19