Sure, the 9x19 isn't going to kill a bear, but I fell out of a plane into any major city on Earth with empty magazines, I could readily get them filled. You can carry obscene amounts of rounds compared to the larger stuff.
-Stopping power: My definition of stopping power is a shot through the front teeth into the medula oblongata. There is no handgun round which will knock a man backward, so true stopping power lies in accurate shot placement, rate of fire, and time to return to aimpoint. If the target is standing still, I'll go with a .500.
If he's chasing me around the kitchen with a frozen turkey, I want 9x19.
-Size: Hard to say. The Judge is not a large handgun, makes a big wound, but you don't have much capacity. You have to hope that your attacker only has 4 shots.
-Loadings: 147 gr +P JHP makes a fairly wide, very deep wound in gel. 17 of them make hamburger.
-Brand Support: Come on........
-Use in multiple situations: I used to advise our pilots that they would be best off carrying a .22 so that they could kill rabbits and pigeons and such, as they were definitely NOT going to fight their way out of Iraq, Serbia, Lybia, Somalia or Iran with a damned pistol. From a handgunular standpoint, I'd shoot a hog with a 9mm. Many, many times.
For defense, I already CC with it, so I'll leave that for discussion.
-Price: Ammo is way overpriced, but wrt the other calibers aside from .22, it's dirt cheap. Reliable weapons can be had for approximately $300.00.
-Worldwide availability: Discussed above. 9x19 is like the Swine Flu. Everybody has it!