I too like when backpacks can be opened like a suitcase. It’s a nuisance having to unpack to reach something at the bottom.
I have two small Osprey backpacks. One is a work backpack optimized for carrying computer, tablet and stuff like that. The other is an almost weightless spare backpack that we have in the car for when we venture out to have a picknick or need extra clothes while on a trip. Folded, the backpack fits into a jeans pocket. Still, it's very durable since its made of ripstop nylon. Osprey makes great gear.
In addition, I have a couple of other backpacks for different uses. One, I think it’s a 65 liter Karrimor, I used for week trips hiking in the mountains of northern Sweden in the 90s. Back then I had to carry a tent, sleeping bag, cooking gear and food for the whole week. I think it's been unused in the garage for 20 years. 🙂 It has been to Australia, New Zealand, Singapore and the US as well, but not on my back.
My current daily use backpack is a Fjällräven High Coast Trail 26. I use it for shorter trips, up to a week, as well. My main reasons for choosing it was its shape, large openings, carrying comfort and durability.
Unfortunately, I’m a bag and backpack junkie so I have had many different ones. 😀 A couple of recent ones I remember:
» Haglöfs Vide Large
» Haglöfs VIKE 25
» An older, better looking version, of the Haglöfs Backup 15 inch