Since we're all shilling our favourite backpacks:

I've been using an Ikea Varldens for the past 6-8 years. Very efficient for my use case (2 work laptops, groceries, travel luggage, documents and earbud case, tools). It has a couple of nice small compartments and a single large one so it's very light for the size and material. Until now the only thing that's annoyed me was the long straps when riding a motorcycle, so I ran cable ties through the loops to stop them from slapping my hands and sides. It's seen quite a bit of abuse and it's still intact. It's even practically waterproof.