I'm probably about to scadelize people, but check out LL Bean's Continental Rucksack. The standard version is about 40 bucks, and I've had mine for over a decade. If you need more room, strap a "mine bag" or something similiar to the top by the compression straps.
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-IronRaven
When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.