There are many camera packs, but most do not have adequate suspension systems for a full camera kit and also tend to lack the capacity for non-camera essentials (layers for cold nights, food, rain gear, etc.).
Atlas has put a real backpack suspension system onto a bag that is highly flexible and tremendously versatile. I particularly like the origami fold system in my Adventure pack. It allows me to adjust the volume distribution between the rear camera section and the top compartment to fit my needs. I keep my long lens at the top of the camera compartment; if I don’t need to carry the long lens I can fold down the first fold of the origami and increase the volume of the top compartment.
Atlas Adventure Camera Backpack - Expandable, Travel-Friendly for Photographers w/hip belt