I have a ratty USMC 3 day assault pack. There are some features that I think are really good. It comes with a stiff plastic insert behind the padding keeping anything hard or that has protruding parts from coming through and pressing on your back. The shoulder straps are ergonomically shaped, well padded, stiff and well padded. The shoulder straps have convenient chest straps. It has compression straps to shrink the pack down and prevent rsttles. It’s MOLE so adding stuff is easy. The main compartment is big enough to hold large items.
Down side is that it has only 3 compartments. The new models have a compartment for a hydration bag.