One thing failed to be mentioned is the fact that DS spokes also suffer all manner of abuse from the chain. What percentage of wheels in use have ZERO damage to DS spokes? I don't think it's that high. In other words, the damage caused by the chain to the DS spokes is also a factor in spoke failure on the DS. Stress risers caused by chain damage account for a significant percentage of DS spoke failures.

In my 40 years of riding, I've replaced probably almost half of my broken spokes on the NDS. Majority on DS, but not my much. And in the shop I was always surprised just how many NDS spoke failures I saw. Given the majority of the loads and stresses are taken by the DS spokes, I simply always assumed they'd always be the ones failing. But this wasn't the case.

In order of effectiveness (according to Wheelsmith many years ago, rim width was the biggest factor) in my book:
(Hub type - usually not an option. But a dishless wheel for the rear is ideal, but often impossible, given today's "more and more cogs" designs.)
Rim width
Rim strength, weight and type (offset spoke holes)
Spoke count
Spoke type (double or triple butted)


(And this assumes the wheels are built by an experienced builder who uses a tension meter and knows how to fully stress-relieve the wheel and spokes. Brass nipples, preferably with locking compound and/or thread prep.)