I just wear an old North Face backpack. It has a chest strap and bungees to constrict the size of the pack. The most important thing for me, apart from the chest strap, is that the pack be full (or those bungees be cinched up as tight as possible) to minimize the movement of gear inside. As I'm typically carrying a full change of clothes, shoes, and lunch containers, that's not difficult for me. Also, I try to run upright with minimal upper body movement.
I hear great things about the Osprey packs, but haven't gotten around to getting one yet.