I prefer the Automatic Assault 12 Gauge, or AA-12 for short.
It's a fully automatic 12 gauge shotgun with excellent door breaching capabilities, and you can also put a 20rd drum on it. Give me two of those, and I can kill god.
I would recommend using incendiary rounds to make sure that they really suffer before dying. If you shoot from a far range, they will slowly burn to death after contact.