They are the most popular law enforcement pistol in the US for a reason i.e, they work (most of the time), have a simple manual of arms and are robust in construction.
That said, over the years, I've had to send a total of six pistols back to Glock with various defects. Two were replaced, two were repaired and two were "upgraded".
Customer service is excellent with a short turn around time.
Keep your Glock stock, feed it quality ammunition and only use unmodified factory Glock magazines and it will serve you well.
My favorite is the Gen 3 19. Second choice is the Gen 4 19. Have tried a Gen 5 19 and don't care to own one.
