My vote for courier bags is the Bailey Works line. Had an old Patagucci Critical Mass Bag for years that was big enough for work clothes and groceries on the way home, but not water proof. Bailey Works is a step above Chrome IMHO. I have a XXL Super Pro for work clothes and lunch with room to spare. Solid workmanship, made in USA by hand one at a time. Check out the DeMartini Globe for the original messenger bag design.