Azazel >>>>> Cthulhu > Raiko (x-mas) >>>>>>>>>>>>>>>>> Ares
Cthulhu doesn't wipe boss Rage gauge, her Charm turns into something that when it stops a boss from taking a turn it will also wipe the Overdrive blops. So first you actually need to land Charm, and then it also needs to proc. It IS super good though, as I've AAB'd through Fire Rag and not been Overdrive'd once. That usually doesn't happen, but it can. Cthulhu also powers up quite nicely in other aspects as well, especially her blop-eater is now ridiculously good.
Azazel has the best Awakening in the game though, period. Do you know how strong Hercules is? What if your entire team could be Hercules? Well, that's Azazel Awakening. The only downside is that you'll need to manual if you want her buffs to come out properly.
Raiko is about to get Awakening next month, and she is already Thunder core. And she gets a super good Awakening too. So a 10/10 Hime turns into 12/10.
And lastly, fuck Ares. She's decent once Awakened, but still sorely lacking.