The Headway MLC (Maximum Legal Carry-on) from Patagonia is a very functional gear bag that works better as a duffel due to it’s uncomfortable (but hideable!) backpack straps.
Other Bags to Check Out:
The Monolith Weekender from Heimplanet is one of my favorites because it is very durable and simple. Carries all your shit, and comfortably!
Miles the Duffel 40L from Millican is a sturdy little companion for travel (so long as you don't have to walk long distances with your bag!).
The Topo Travel bag has a playful style, which I like a lot, but it is very serious about being a great travel bag. This is a classic.
The Knack Pack from Knack is a surprisingly great backpack for both daily carry and travel... it expands and collapses and has a solid look for professionals out there.
Is this just, like the most quality built affordable carry-on travel backpack? It just might be.