UPDATE: After a few years i still love them both! I have a long-term review of both of these bags coming in a few days! stay tuned.
I could not find anywhere on the internet a review of these two bags so I decided to buy them both to figure out what it was that I wanted. Both bags are premium bags that will protect your gear and look good doing it! the value of the bags to you will depend on what you carry other than your camera. The ONA is larger and accommodates a laptop with ease. it also can accommodate a small DSLR and 2 lenses. (a larger pro body DSLR would be pretty tight in the Union street and you can forget about it in the Billingham Hadley Pro.)