I'm not going to recommend a particular type. But here's a couple things to keep in mind. I assume that you're primarily thinking about bears and possibly mountain lions. Bears are FAST. If you have to defend against an unexpected attack (i.e. the bear/mountain lion charges immediately upon seeing you), you'll be veryluckyif youget off 2 shots.
Also, depending on the time of year, elk and moose can be very dangerous as well. Again, they're a lot faster than you might think.
So in general terms, I would recommend stopping power over capacity. Just make sure to practice enough to get very comfortable with the recoil.