A long time Glock shooter and Police Officer here...
Suggestion: start with stock trigger and learn the Glock trigger and releasing the trigger just to reset ( don't release all the way out after the shot only until you fell/hear the click
Of the trigger resetting). This will get you faster splits and follow up shots.
After you are comfortable with the trigger, google the "Glock 25 cent polish job". Steps on polishing parts of the trigger bar and connector which will make the trigger smoother and a bit lighter.
By doing the above, along with LOTS of dry firing you will smooth up the trigger.
After this (and it takes lots of rounds and dry firing) then look into aftermarket parts.
For aftermarket I suggest:
1) Zev tech competition spring pack and V4 connector - this combination will give you about a 3.5 - 4 pound trigger pull that is smooth with a very crisp trigger break (break will feel like a small glass rod snapping...that's what you want).
2) Zev tech drop-in trigger assembly - same as above but with a better trigger bar and over-travel and pre-travel reduced.
3) Glocktriggers.com - Vogel competition trigger - smooth, crisp, and light (about 3.5 lbs).
4) Vanek triggers (
www.vanekcustom.com) - drop in competition trigger that is VERY light, but a bit soft/squishy coated to others listed above.
I've run homemade .25 cent jobs, Vanek custom and they are nice. Currently I'm running option #1 above (Zev tech competition springs and connector) and I like it.
Bottom line: start stock and work your way into custom. This way you learn the trigger and gun and develop sound fundamentals. If you jump right into custom and don't shoot well you won't know if it's that particular trigger combo or your fundamentals that are off.
Hope this helps. Glocks are great tools, can be very accurate, and can be worked on by the average shooter pretty easily.
Enjoy!!!
Z-