I carry a .357 mag short barrel 5 shot. It will stop anything I will encounter, even a black bear. Although it wouldn't be my first choice for bears. But it will work in the off chance I would need it. So if you want to carry a revolver, I would recomend at least a .357 mag. If you prefer semi auto's then I would go with a .40 sw. It is almost the same as a .45 but holds more rounds. And then if you think you need bigger then go bigger. But under the defense issue the revolver is probably the more reliable way to go. That is just my opinion.
Buck