The .45 vs .40 vs .357 Mag vs 9mm debate has been going on as long as the cartridges have been available.

My opinion for what it is worth is all of them will provide a fatal shot with good placement. The way I would answer the original question is which one do you personally shoot best with rapid fire follow up shots? That is the best cartridge for you.

Me personally, it I must use FMJ only I prefer .45 but that is just my opinion based on my experience. Test them both and decide based on your experience.