If the accuracy was par for both the 50AE and 44mag, and you gave me the bullets, I would go with the 50AE. It does have a tad more punch and hey, I have only used the 44mag for hunting and doing it with a 50AE would be interesting. If I had my own reloads and had trouble finding the 50AE, 44 without a doubt.

Now with the 50S&W, no contest. its the badest, pistol around. You have the killing power of a muzzleloader at 2100fps Muzzlevleocity with a 300gr bullet. 44 doesn't come close. As long as you can handle that bruiser.