Osprey aren't great for proper long distance hiking with 15kg+ which you'll reach if you're bringing tent + food for two and a water bladder.
My friends got their 65L bags and the shoulder straps caused some serious pain, granted they were tools and overpacked their bags hideously so that didn't help.
I'd recommend the Lowe-Alpine 35-45L bag:
http://www.gooutdoors.co.uk/lowe-alpine-airzone-pro-35-45-rucksack-p269841
You can shop around or use price match to get it cheaper, I got mine for £70 with a price match.
Osprey are budget bags, they're good budget bags, I use a day-pack style 30L for commuting/trips to the family etc but for actual hiking you need to consider it an investment unless you want some serious back/shoulder pain with a heavy pack.
First time I've heard of osprey bags being "Budget"

It may well just be that your friends didn't pick bags that were designed for their shape or the weight they were carrying. I find the lightweight straps on the atmos very comfy, but I know others hate them.
Like most technical outdoor gear it's best to go to a decent shop (Cotswold/Ellis Brigham/snow and rock or a decent independent) and try various bags on and see how they fit. Several manufacturers now do back customization (heat usually) to get the bag as comfy as possible for you.
Like most on here Id recommend no more than a 45-50l bag as that is all you should need for even fairly long multi day hikes. The problem is the bag is only one part of a decent system. You'll also want to be getting a lightweight tent (~2kg or less for 2 people), sleeping bags, thermarests/pads, cooking stuff (the MSR pocket rocket is awesome and a great buy, along with primus cooking pots (ones with the fins on the bottom) and a multitude of lightweight stuff. It shouldn't cost too much to get an entire weeks kit down to 10-12kg (exc water).
Which brands - Osprey, Berghaus, Deuter, Lowe Alpine are all good. Which one you buy should depend on what fits best and what one best fits your needs. I have a 35l atoms and it struggles to carry more than about 15kg comfortably, but it's a lightweight bag, designed for lightweight hiking*, Osprey do heavier bags designed for more weight if you really need it - but then you're just inflicting pain on yourself if you really need more than 15kg!
*My kit is about 10/12kg wet (with food and water) but I usually carry about 3kg of camera equipment as well...


It was the South side of Loch Rannoch I was at. We had the hammocks pitched near the top end of the Black Wood...between the black wood and the Dall burn. I've been up there a few times and it's absolutely stunning. The only other person I saw in 3 days was someone who came through doing an ant hill survey. That's amazing that you've got a place there. Jealous doesn't even cover it. 