Access is the issue for hiking packs, but if you don't mind taking the pack off your shoulders, the Mystery Ranch "Y" zipper panel access series of packs accommodates large padded inserts.(for example, this: https://www.mysteryranch.com/scree-pack )
The Osprey Kestrel line of packs open from both the top and back...just like the F-stop bags. I find access even easier with my Osprey than my F-stop bag.