I guess it all depends on what the conditions are that you will be hunting. How far will the shots be? If you are going to shoot beyond 150 yards, a .270 on up a .375 will be fine. I would probably recommend a .30-06 since factory ammo is easy to find anywhere in the world. If the shots are closer and in thicker areas, don't rule out the .45-70. This caliber gets no love but I really like my Marlin in that caliber. It would have no problem taking down a bear and I don't have to track a deer when it gets hit with a 300 grain bullet. It would also make a great Elk rifle which I plan on hunting next year.