I vote 44 mag. But like other's said, both are good choices. I see more 44 caliber reloading components than I do 45, and the 45, like others have said can have throat sizing issues.
I carry a 10mm with 200grain bullets around 1230fps. Which gives 671ft-lbs. It's not easy to get that velocity out of a 10, and almost always requires a 5" or longer barrel. I like revolvers, a lot, but they are just so damn loud. Even with ear pro. If it was a charging bear, there's no time for ear pro.
Someone asked for the formula for energy. Here it is...with all the units already converted.
(bullet weight in grains x bullet velocity in fps x bullet velocity in fps)/450470
