I asked this question on rec.bicycles.tech back when I was still using USENET. DT and Sapim seemed to be the two top choices, Wheelsmith was a distant third, with some negative comments about the shape of the transition from thick to thin sections of spoke. My (limited) experience with DT and Sapim has been excellent, Wheelsmith not so good. I like the theory behind the shape of the Sapim Polyax nipple, supposedly the rounded shape lets it sit in the rim better.

Are you getting a new rim as well? What about the hub? Rims tend to wear out when you ride on dirt roads or in the wet, all the dirt acts as an abrasive whenever you apply the brakes.

As Sixty Fiver pointed out, the skill of the wheel builder is at least as important as the quality of the parts.