The Glock 19 is one of the most popular models for a few reasons:
It’s chambered in 9mm — a widely available, relatively inexpensive round with excellent ballistic performance and lethality for self-defense applications.
Its 15-round standard capacity is advantageous in home or self-defense scenarios.
It’s a compact build, offering a happy medium between smaller, subcompact pistols and full-size builds (but this is true for multiple Glock models).
As one of the most popular models, aftermarket components for the Glock 19 are widely accessible.