It depends where one lives. In Ohio, a .357 magnum with a 5" inch barrel allows one to hunt for deer with it. You can plink with .38 wad-cutters or load with one of many personal defense loads for two legged predators. You can even get one with a 7 or 8 shot cylinder if you prefer.
If one lives in grizzly country however, a .454 casull with at least a 5 inch barrel is what I would carry.