The Automag II .22WMR and Automag III in .30 Carbine are the most sought after, as these are the most common cartridges, and are the least painful to shoot.
The .22 Magnum is pretty gentle, but makes a nice bang and fireball, and the .30 Carbine is generally milder to shoot than your typical .357 Magnum revolver, owing to its large size and substantial amounts of powder not getting the opportunity to accelerate the bullet, rather just blowing out the muzzle as a rather larger and loud fireball.
The Automag III in fact delivers pretty piddly ballistics on that account (.30 Carbine is just made for much longer barrels), and would pale in performance next to its 9mm Winchester version or any typical .357 Magnum
The Automag II was not short-recoil like the others, instead straight blowback, and the slides all have cutouts on them, presumably as they would be too heavy to cycle otherwise. Their Automag II also has a set of little pits in their chambers, where the brass will expand slightly into as it fires, which the action has to force to straighten out during extraction, presumably to make sure that the pistol doesn't extract too fast. Looking at fired casings from these pistols, you'll notice these marks on them.