My neighbors have gone in all directions at the same time, telling me there is no one best way.
Drilled will shade out weeds sooner, but takes more seed ($$$) and subject to white mold easier.
30 inch rows the planter iuses less seed, less disease, but a little tougher on the combine head and might take an extra spray pass. But - you don't run down the beans if you need to spray later for weeds, insects, or fungus.
I'm happy with the 15 inch rows I do, compromise of the 2.