I would always choose Osprey over Camelbak.
Arguments I mention below concern my personal experience with Osprey Raptor 14 and Camelbak Mule
Osprey:
+Lid-lock system for helmet on all Osprey MTB backpacks
+Best storage capacity among all the backpacks (important for long distance biking)
+Great fit
+Improved airflow
+Included tool roll that stows in a dedicated pocket at the bottom of the pack
+Reservoir and hose routing is more accessible
+Improved compression straps and over all stability
- Pricey