IME/O, the Perfect is better for rifle cartridges because it'll dispense enough powder in one drop to fill them. I use a Perfect for my rifle reloading. The Auto Disk (I have and like the ProAuto Disk) is oriented toward pistol cartridges. The Perfect could be used to charge pistol cases, so long as you don't have too small a cartridge, and/or don't want too small a charge. Using the double-disk version/system on the ProAuto Disk measure, you can satisfactorily charge 223 Rem-sized rifle cases. I'm not certain how much larger you could go, as that's the largest rifle case I've ever personally charged with my Auto Disk measure.
Another option is the Lee dippers. Lots of folks seem to have a poor opinion of them, but they're extremely consistent when used as directed (read Lee's instructions, but basically you strike them off level with a business card).