Hiking backpacks come in two different styles, External Frame and Internal Frame, and each have their advantages and disadvantages. To be clear, I am bias. I'm old school and started backpacking when I was 12 with my Grandpa. I've always had a Kelty External Frame Pack.
I like how organized it is and how it keeps it's structure. I can remove one thing or everything and keeps it form. This makes it easy for me to unpack at night and easy for me to pack-up in the morning. Because I don't need to pack it in any particular order, I don't need to unpack everything every night. Everything has it's place and there is a place for everything. The external frame gives a structure to grab and manhandle my backpack without putting stress on the shoulder straps. Since I have a frame, I can strap anything and everything to the frame on the outside. i.e. Tent, sleeping bag, pad, clothes, whatever. This frees up a ton of space inside my bag. Plus, the external frame has amesh screen across the back that keeps the pack itself off of my back and creates an airspace so my back can breath.
There are 2 downsides to the External Frame Hiking Backpacks. Since the shoulder straps are attached to the external frame, any shoulder movement causes the pack to shift. It's not the pack for climbing, using ropes, or anything that requires moment in your arms or shoulders. The 2nd downside is a big problem for me. They simply stopped making large capacity external frame hiking backpacks. You just can't seem to find them anymore. I assume because the Internal Frame Backpacks are winning the battle and are more in demand.