Both seem to be getting a limited pre-release at Games Day UK. The Kakophoni appear to be the precursors to the Noise Marines, while the Ashen Circle are assault troops with flamers. Of the two I must say I would take the Ashen Circle since I am not that big a fan of the Emperor's Children.
The Word Bearer's Ashen Circle
Word Bearers Legion - The Ashen Circle
The Emperor's Children Kakophoni
The Emperor's Children Legion Kakophoni