If you don't reload, I recommend you go with the .224 Valkyrie. I shoot 60 grain Ballistic Tips out of mine and it is devastating on varmints/predators. I've also been using the Sierra Prairie Enemy ammo with their 69 grain Blitzking. It is a great combo. Besides coyotes and varmints, I used my Stag15 and the Sierra ammo to kill a Doe Antelope at 468 yards last year.
I also own a .22 Nosler and like it a lot, but for someone who does not reload, it can be hard to find loaded ammo at times.