The 6inch is best for a hand auger. I would recommend the Strike master Lazer hand auger (don't remember the cost) it is a very good auger for the money. A 8 inch for the power auger and even tho a 10 inch auger is legal in Pa, it is dangerous to have a bunch of the 10inch holes around because little kids and women and some guys can get there foot in those holes and they can get hurt or worse.