Just my opinion, but generally-speaking, you want them at whatever angle your wrist isn't going to be bent when your hands are in the hooks, and then your levers should be positioned so they are reachable from there as well as from the hoods.

Your wrist position when in the hooks matters more than when on the flat part of the drop because that's where you would expect to hold the handlebar most of the time when riding in the drops (so you can have quick access to the brakes).