My priority would be: back and neck protection that is as easy to wear as a helmet. All other injuries worry me less.
I went backwards on my bike this past weekend and did a full backwards somersault. Until this, it never occurred to me how protective a hydration pack can be. I would have been all done, but thanks to the pack, I got right back up on my bike and completed my whole ride. Unfortunately, the phone that was in the pack didn’t survive the crash, but better the phone than my spine!