I've been using the Maxped Fliegerduffel for a few weeks now and love it. It has a lot of carry options. Backpack straps which are pretty comfortable. It has a D ring on each corner so you can choose how you want the long shoulder strap for one shoulder carry. It has a padded single hand grip on top and a drag strap on each end.

Would make a great BOB. Tons of molle webbing and five pockets besides the main compartment.

Highly recommended. I assume the Doppelduffle is just as good, just bigger.