The pre-eminent dynamo light on the market includes a handlebar-mounted USB charging port, so you can use your dynamo hub to power your smart phone or an external battery either with the light on or (preferably, for faster charging) off.
Luxos is the light to get if you ride where there aren't any streetlights and/or if you ride at high speed. The beam width widens the faster you go. Because it also cleanly charges your smart device, GPS unit, or external battery pack, this is very much THE light to get for bikepacking.
Although some people successfully use the Luxos U with Shimano's 1.5W dynamo hub, we recommend using the standard 3W hubs from Shutter Precision, Schmidt, Sanyo, or Shimano.
The only tail light we recommend with the Luxos is the B&M Top Light Line Plus with brake light.