I’ve used a lowepro photo sport 200aw a lot when guiding. Super comfy and great access for camera. There is a pro (30L) version with a removable camera pod which looks even better, and also a new photo sport 200II which looks good.
Tip: I found that when biking, taking the aluminium rod out of the back allows the pack to hug your back better and it moves around a lot less. For hiking and climbing its better with the rod in.