What is advantage of using Dryad instead of Spark? I found that Apache-Spark very powerful in Big-Data processing. but I want to know about Dryad (Microsoft) benefits. Is there any advantage for this framework than Spark?

Why we must use Dryad instead of Spark?
Dryad is an academic project, whereas Spark is widely deployed in production, and now has a company behind it for support. Just focus on Spark.