G19. I use cheap Remington UMC ammo at the range and Federal (+P+ ) 115 grain JHP for defense. I read about this ammo on a law enforcement ballistics report online. That report mentioned a few different brands with similar specs. The Federal turned out to have a good deal on Cheaper Than Dirt. I love the 19, but am considering using .45 out of concerns about wall over penetration.
Between the '17 and the '19, we are only talking about what, a half-inch difference in barrel length? Since CC is not a consideration, I'd recommend the '17. That extra half-inch helps allow the bullet to develop the maximum pressure of the cartridge (whatever is loaded) and the longer barrel helps with accuracy shots, with 2 rounds more in the stock magazine than the '19. Some practice with good retention techniques should negate any disadvantage of a larger weapon in a struggle. For close-in applications like home defense or CC, one could look at 90-gr XTP bullets zooming out at 1,500+fps on the low end or 147-gr XTP bullets flying at 900+fps at the high end. I would have my reservations about the 90-gr bullets' ability to knock down poppers, though.
