I would go with the reg .300 Wmag, itsbetter than any of the others IMHO. altough all would work well, the mags have more velocity and thus more power and flatter traj. the .300 is just a tad better for moose than the 7mm mag due to the heavier bullets, but they are still very close. If you find a good used rifle in any of the cals buy it.If buying a new one I would get the .300 wm.