I would go 308 or 30.06. I have both and would hunt anything in the lower 48 with either. If i was going after big bears that would be the only case in which i would get a .338 or something bigger (brown bear, etc..) I just don't see any reason to deal with the recoil of a 7mmmag or 300 for deer or black bear. Alot will depend on the rifle thou, recoil pad... But i tend to stay with a lighter rifle, bolt action Savage, Winchester M70, or Remy. I have found that my savage weather warrior in 308 to be my favorite rifle.