204 Ruger, I have had three, Rem VSSF II, XR-100 and my Tikka Super Varmint I am selling. They were and are super accurate and just drop coyotes, I will shoot more rounds in a day at gophers, than I ever will at Coyotes so it is dual purpose, with out the extra cost ammo, powder, and recoil like some other cartridges.
That being said I have a had quite few 223s, that are also great,, the one good thing about buying guns or selecting a caliber, you are never stuck with it, you can buy and sell and pick the one for you.