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 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.
The Homebase series from Tortuga features this incredibly lightweight sailcloth material that's water resistant and super strong. (It feels light and scary! But it's damn strong stuff.) This makes for an incredibly light and resilient travel 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 Allpa 35L travel pack from Cotopaxi is a well designed carry-on backpack with security features, solid organization and durable materials.
The Black Hole Duffel from Patagonia is called the "black hole" because it fan fit all your stuff.