I don't know about coolest, but I think that Aphrodite is definitely the most dangerous. The power to make people fall in l’amour with each other, and other powers like that !? That's pretty damn dangerous if toi ask me. I wouldn't want to get on her bad side.
Hades why toi may ask beacause hes like the outcast olympian he owns the Underworld he has the helm of darkness he has an uber powerful sword which toi see in the demigod files he controls the dead and HES BAD ASS!!!!!