RE: whitetail deer and black bear caliber
Most of the all around calibers will work well. This would include but not me limited to the 270, 7-08, 280, 7MM Mags, 308, 30-06, & the 300 Mags.
If you aren't a handloader I would choose the 30-06. Ammo is available just about everywhere and there are a plethora of loads available.