I think there are some valid comments to questions not asked.
Robergel spokes got a bad rap, although I never had problems much. I did find the nipples soft, so a perfectly fitting spoke wrench was needed. They also used unique threading, so not as easy to stock, especially now. Biggest problem was when truing a rear wheel, was the spoke frozen or was the nipple deforming? Only a third of a turn later did you really know.
DT became my favorite, better nipples, my spoke of choice since 1975. Around 2000 I noticed a change, it is documented here pretty well:
http://www.peterwhitecycles.com/
For new production spokes I have used Sapim, fit well, and a blank spoke head.
I have also used Wheelsmith, without problems.
All I have used are factory threaded spokes with rolled threading. I cannot comment about the threading machine results.
John Jorgensen
Torrance Ca USA