choice
The .223 is likely a more practical choice, although if I saw a lot of deer or hogs in my future, I might opt for the x39mm verison. I've got bolt rifles in each caliber,and the .223's see far more shooting. The x39 rifle is solely a deer rig for me.
I'd not overscope a Ruger Ranch rifle, by that I mean, no more the a 1" tubed 3x9x40mm sporting scope. To me, anything bigger would detract from the handiness of the tidy carbine. I ran a fixed 6x36mm on one of my Mini Mauser .223 for a while, and often felt as if I wanted more magnification for smaller, distant targets. The 3-9x40mm on it now is a bit topheavy, but makes for a more useful rifle.