Shoot whichever you like better, or is cheaper, or whatever. Caribou are not near as tough as deer or elk. If this is your first hunt for them you will be surprised how easily they fall. Any deer cartridge would be fine. I bowhunted them the last time and they never went more than 70 yards. All of the rifle hunters virtuallydropped them in their tracks, and some of those shots were far from perfect. It is awesome country up there and just awesome if the Northern Lights come out. Best of luck to you.