Certainly the .45acp would be more effective. Since both have the same capacity, which is to say not much, .45 is the way to go.
Keep in mind, as has already been pointed out, it's not going to be much better than a handgun anyway except maybe in terms of shoot-ability. A good AR15 is a better choice but they do cost 5X as much. But it has a HUGE advantage in every other category except weight where it's probably a draw or dang near.
I don't collect guns, I accumulate them.