6.5CM,308,243 I myself would not call these colony varmint rifles. All are pretty low recoil, let me know what ya think after 50 rounds in a couple of hours.
The OP mentions P dogs, easy peasy gotta point towards the 223. Even a long throated fast twist can be useable with some designs of 50 and 55's and could be pressed into service for other critters.
Bone stock out the gate varmint only 204 Ruger.
As to a platform, ya get what ya pay for. Worried about what it will bring if you sell it later on? Go Savage, if you can put gas in a car you can swap bolt faces and barrels.
Maybe not the best actions in the picture, but for darn sure not the worst.