IMO, don't use anything. Your out in the backcountry, not going on a date. Soaps, scented things, those don't belong out in the backcountry when hunting. Those very unnatural smells can theoretically be detected by animals you are trying to hunt.
If its an issue of you sweating profusely and getting chaffed etc in and around your arm pit area then i recommend using something like gold bond powder, or even body glide. But in general would stay away from anything with a scent. I don't know for sure how big of a deal scent really is, but i am sure the more you can do to "mask" it the better your odds. Though i am still not convinced it makes a huge difference, but am sure it does to an extent.