From my research, most are pretty crappy. Either they are not comfortable, don't have room for other gear, or they don't protect the gear very well. Gear access is a huge issue.
My solution was to use my normal hiking/backpacking backpack and then add a Lowepro toploader that I attack with carabiners. I have the Toploader 65 and it has enough room for camera body, zoom and wideangle lens, remote, batteries, etc. And if I really need more gear I stick the least used in my main pack. It also has a water resistant nylon cover (vital for the northwest).
The best part is it's not on my back when hiking or backpacking, so if I'm trekking along I don't have to stop, take off my pack, and dig in for the camera. That's ok sometimes if I'm trekking alone but never in a group when we have a destination to get to. It's right in an accessible pouch on my chest that I can get into while still moving along. Many times the photo opportunities disappear so so quick you lose the shot if your camera is in your pack (wildlife, etc.)
I'm sure there are other brands out there but I'm very satisfied with my toploader.
As an added bonus, when I have a 40+lb pack on it helps keep my weight centered better.