Swedish brand Fjallraven have an iconic backpack style - as iconic if not more than the eastpak backpack. Its a simple polyester bag with an iconic round red and white logo and my favourite part is the two thin handles than hang down and button together with a mini-handle wrap.
These bags have established quite a cult following. You can check out them as well as their extended range on their website: http://www.fjallraven.com/
This is of course, an Eastpak backpack but i just wanted to show it here alongside the Fjallraven backpaks to illustrate how this simple style backpack has come back into popularity big time.