I was looking for a quite big rucksack as I'm planning to travel for a few months this summer. I found the cheapest option on Amazon with this Linchfield Explorer 80+10.
I received it very promptly, and am very satisfied so far. It is, indeed, big, 80 liters being more than useful if you intend to bring lots of things with you. It seems nicely organized not to hurt your back, and the ergonomy appears me quite satisfactory.
Any weaknesses though? Yes I would say so: first, there's an unfortunate lack of waterproof cover -which I recommend to buy as an extra, except if you're sure there won't be any rain during your journey-. Second, the relatively low quality makes me wonder if it'll resist years of adventures. I would suppose not, and if your plan is to go hiking in tough conditions, you'd better buy something more professional.
Otherwise I think it still deserves four stars, since in normal conditions I'm sure its quality is actually suficient to cope with one's needs, and besides the price is so low it's a very good deal.