Is it even a close comparison? Are there some situations where one is the go-to model over the other? Which situations are those?
They both have sprays, but Skerath gets the Banshee-like Dahlia. Discordia gets the defensive aura. Skerath doesn't drain your focus. Discordia gets all the "friendly faction model" stuff (not that a large-based spray model could really benefit from ranked attacks, but there are others).
What's the consensus? What's the dissenting opinion? Why?