Unless you are a benchrest shooter there isn't going to be an appreciable difference in the inherent accuracy of the two cartridges. Both are adequate for the purpose you are going to use them for. However I would go with the .22-250 simply because it lets you shoot heavier bullets faster at longer ranges than the .223. For example a 60 grain bullet from a .22-250 arrives at 300 yards almost 300 fps faster than the same bullet shot from a .223. The higher velocity should make for more humane kills on coyotes. The .22-250 had an established reputation for long range varmint hunting before anybody even dreamed of the .223.