LOL, that is a question I have asked many people, and just about nobody has a good answer.
Either way works, in my experience. I always install them with the longer radius sweep receiving the discharge from the fixture, to cut down on turbulence.
I would get rid of that cheap plastic hanger strap. Use metal strap, at a bare minimum. And if that is PVC on the cold water line, it won't pass inspection under any code I am aware of.
