I had the same problem as you. I tried three different cords - a cheap $6 one, a Monster one, and a bluetooth no cord aux one, and they all in a way sucked. Here's what I found was the best.
It's flat so it doesn't get crushed when you close the arm rest. And the sound quality is absolutely perfect. Of course if you get your music from YouTube the songs will be s**t quality, so thus the hissing. But if you have pretty good quality music then this cord will have absolutely no hissing.