Totally agree - compared to suitcases, backpacks vary even a lot more in terms of storage strategy and what’s a useful separate pocket for one person is a waste of space for another. It’s almost like those multi pocket jackets.

Comfort notions are also very personal when it comes to backpacks (the back is a vulnerable part of anatomy for many of us), whilst there is a huge difference between someone who use a backpack exclusively as second bag and someone who sometimes uses it as sole bag as I do.

personally, it’s one thing I’d never buy online - I like to see them, try them open every pocket back and forth etc. I’ve got two I seem to use all the time. One is about 20 years old of a major brand, bought when its predecessor died on me in Stockholm, where it was decently discounted, and in a terrifying state including one small pocket which stitching has been too damaged over the years for me to use it to keep anything but plastic bags - and one which is at least 10 years old and cost me under £10 in a random bargain shop in tel aviv when I was looking for something cheap and cheerful to use as beach bag.