Good Quality Rucksack / Backpack (off the bike, hiking)

I just picked up an eastpak floyd from amazon for about 25 coins, and it's actually fucking great. Lots of nice detailing, like side pockets that can be zipped away unobtrusively, and really effective compression straps.

Thats the bag I've used for my cycle commute for the last 5 years.
Great quality - feels like it will last forever.