I currently have 5 camera backpacks. All have gear in them, but I switch the contents depending on the trip I take. At this time, I’m traveling through out the USA and simply need to carry a 13″ Macbook Pro, 2 bodies, 4 lenses, one portable flash, carbon fiber tripod, memory cards, batteries, chargers and other small accessories as well as a rain cover just in case. All of the gear I described fits in a canvas backpack that looks closely like an ONA a Backpack.
I’d recommend this backpack but the inserts that came with it are too soft, the inside needs to be more rigid so your gear doesn’t go everywhere. The point is to keep your gear safe and secure. So I replaced the original inserts with LowePro inserts and now its great.