Thank you for all the response. I'll definitely try out the Osprey backpack. They might just work for me. I'm just afraid that the weight will be too much for me as my doctor and my comfort doesn't allow me carrying more than 20 pounds and having a pack that weights already more than 3 pounds gives me less space for other gear and food.

I'll also follow the advice of all of you and order two packs in my list - the zpacks and GG Gorilla. Unfortunately I'll have to scratch the KS Ultralight as they're located in Japan and returning would be too expensive.

My base weight: 7 pounds (excluding backpack and bear canister)
Weight with water and food: 13-18 pounds, depending on environment and distance to next re-supply location and/or water source.

I'm preparing for my PCT thru-hike attempt next year.