Which is better, Chevy or Ford? :) :) :)
If white mold is a concern (heavy wet soils?) then the 15 inch will be a little better - more air to the stems.
Be a little cheaper buying seed with the 15 inch planter, a planter places the seed out there, while a drill on narrow spacing spills the seed out there. But of course, the planter will likely cost more than a drill....
Lof of folks went back to 30 inch around here after playing with a drill, seem they do well with the 30 inch and have good yields.
I see all three around me - drilled, 15, and 30 inch. I'm not sure there is one right answer.
I'm happy with my 15 inch.