Up stream wind on the left bank. You would be crazy to not use a single spey off the right shoulder, quickest way to get the fly back out and fishing. I won't discredit the snap-t as a cast its very useful with very heavy tips and a serious change of direction. But you can achieve the same with the single and use one less move to make the cast. Learn the single and it will be your best friend, practice it off both shoulders and you won't want to use a snap or a double.
Brian, drowning in newf drewl