Since you said rifle hunting I would probably suggest 10x since you will be glassing longer distances and more open country.For a first pair of binos for rifle hunting in Colorado / Wyoming, what do you recommend? 8x vs 10x? Will 8x be enough if using with a spotter?
But there is no wrong answer, 8 with a spotter will work great too. Go to the store and look through both powers of the same model of binos and get a feel for the difference.