Assalamu alaikum, In the case of halaal and haraam where there is a difference of opinion there is only one correct answer. For example lizards and crabs are either halaal or haraam. Either Hanafis or Shafis are correct and one of them is certainly wrong in these issues. As for issue of preference as to what is more superior - then there is only one position which is more superior. In these cases there is acknowledgment that both were done but one is more superior but the other is not incorrect. Like the position of sadl (which I assume refers to having the hands on the side) - either sadl is superior or folding the hands is superior - one of them and not both - but both were done.