For the best design, permanent magnets fastened to the surface of a generator rotor would likely emulate the construction of a wound field synchronous generator. The same would likely be true for the stator design.
In a salient-pole, wound-field synchronous machine, the most satisfactory pole embrace is about 70 to 72 percent. The stator windings are distributed in slots with a certain number of slots per phase per pole. Slots are evenly distributed around the entire circumference of the stator with no unused slots between poles.
The air gap between a pole shoe and the stator iron is smallest at center and somewhat larger at the edges with the edges rounded at the edge.