In the past, my Siren Song was stronger than Power Charging. It's all about building the right amount of stats to hit high damages.
As for grinding purposes, the same can be said about Power Charging. All the AoE skills have a long CD. While PC is a surround AoE and Siren is a cone AoE, Siren has no control issues. You at least know where the AoE is going since you're choosing the target.
I use to chain combo Skunk Pouch + Deadly Funk. It made it impossible for anyone to do anything against me because I pretty much landed the skill 90% of the time.