I’m not the best person to talk about current packs, but you’ll find some are more/less adjustable to different sized folks. If you have to buy a pack sight unseen, make sure high return shipping cost doesn’t catch you off guard.
When I get to a backpacking or big sporting goods store of some kind, it’s automatic to squeeze and fold over the hip belts and shoulder straps.
Some are soft and some are firm. Soft sells well when the pack is tried on empty at the store - firm handles weight better.
Some are wide and some are narrow. Narrow should be avoided, and often extra wide is more for looks, or at least can be. Heavy weight needs a good size belt that pretty firm.
Some have an ergonomic curve sewn in, while others are more or less straight. Curves are more expensive and require better engineering, but carry weight better. Firm belts with a shape that fits you well is ideal.
It’s nice to get an idea of what sizes fit you the best.
I’m 5’9” 190 and have a somewhat short torso so medium packs with large shoulder straps and large hip belt are ideal. My heavy friend of the same height uses a large pack, large shoulder straps and extra large hip belt. Another friend of the same heights but slimmer, uses a large pack, medium hip belt and large shoulder straps. None of us could trade packs and be comfortable.
I’d guess making sure the pack fits your torso length without having too large of belt is the biggest challenge.
The kicker is, many packs try to fit as many sizes as possible and it sometimes works and sometimes doesn’t. If you end up with a pack that doesn’t fit for some reason it pays to call their customer service before getting the pack dirty and they may have a different size they will trade you at no cost. Definitely check with the manufacturer for sizes available, rather than the more limited list of sizes many retailers stock. Heavy packs usually carry weight better than a lighter pack from the same company.
