sorry for the noobness, but what's the advantage of one over the other?
Rev. A adapters use the Atheros 900x drivers, which Atheros does not seem to be continuing the development of the drivers. D-Link seem to also have stopped any driver updates for this adapter.
Rev. B uses the Ralink RT2870 chipset. Ralink seems to be constantly updating their "reference" drivers. By using the Ralink RT2870 drivers, you can have a more recent driver. Not only can the Ralink drivers be used with the DWA-160 rev.B adapter but several other adapters, different models and manufacturers, can also be used. This will help to eliminate the "driver" interference that can happen.
Also, the rev.B adapters are newer tech than the rev.A model.