Incase makes some great backpacks with good padding and a sensibly modern design.
Gravis is known for their skater stuff but their designs work well for cool and casual too. Their ‘DJ Bag’ (as linked) is cool and functional with good pocket organisation.
I wasn’t looking at your q and answered for messenger/handle bags but here are the answers anyways for those interested
ACME bags makes one called ‘The Slim’ that’s a superbly cool minimalist bag that fits a laptop like a glove.
I have a Jack Spade file folder waxwear that I always have with me. Works well as a business case and a casual carryall, is durable, and looks understatedly handsome.
As mentioned above Booq makes some GREAT backpacks too, they look hip and are highly durable with excellent protection using semi-hard materials.