Where your at you must run into just about as many fox as Yotes I would think, are you hunting fur or just killing ? Calling ? running with Dogs ? sitting over bait Or just riding around ? If your just killing (which I have no problem with these days on the coyote's) any of the calibers listed will do a fine job, pick what you like. If your hunting fur that's another story, Most if not all the .22 centerfires are way to big for the Fox. We call up here, most of our shots are well within 100 yards, a very good DRT bullet for a Yote is a 40gr Vmax in a .223 ( Our Coyote's aren't worth much) as long as you get a frontal shot or miss a bone going in, your good to go to sell the bloody thing, nick a bone of any kind going in and they don't make enough thread to sew the hole up, run that same bullet into a fox OR heaven forbid a Bobcat ( both worth quite a bit more from up here) your 9 times out of 10 carring 2pc's out, I've kinda been leaning to the .17 Remington..