I too struggled with the same thing. I have taken everything from 44 mag handguns to rimfire rifles and handguns and everything in between.

While a long arm makes the most sense to me (maybe a lever action in 357 mag?) my current go-to piece is my Springfield XD in 45 ACP.

Why the 45 ACP?

My main fear of predators is of the two-legged variety. At up-close distances I don't feel undergunned with the 45. If I had to take small game I could probably manage to do so as well. I don't fear an attack from a mountain lion or a black bear but if push came to shove having 14 rounds of 45 caliber, 230 grain ammunition available does provide me with a sense of comfort. Finally, the pistol packs and carries easier than any rifle.

Others may disagree with me, but you did ask for opinions, right?