I travel with a canary yellow (summit gold) North Face Base Camp duffel bag. Size medium works best for me. Waterproof, virtually indestructable, super-stuffable, makes a good back rest or pillow for 25 hour boat rides, and the yellow color is easy to spot when all the bags are unloaded and thrown into a pile.
Image above shows my duffel being carried to the Upper Chindwin River in Sagaing Division to be put on the boat for the aforementioned 25 hour boat ride from Htamanthi to Monywa. I spent a lot of time sleeping on it. [NOTE: I've had this duffel for about 5 years. It's a terrific bag].