I like the Titans.
They're brutal, savage masters of the universe who were overthrown by the new generation. They touch on all the cornerstones of my personal beliefs about life, evolution, religion, and reality; but in my games they are one of the greatest villains you can throw at a group.
Demons, Devils, and Daemons are all fine and dandy, but when you beat them you're always left with a game of Buffy the Vampire Slayer - only without anything left to slay. Titans on the other hand are the consummate villains. They're played like humans, with the same emotions and foibles, only they have an unlimited reach to respond to even the slightest insult.
Where the gods are often over simplifications of aspects of humanity the Titans are the complex, dirty reality of being alive. They shake the earth and move the heavens with their passing, and in my game that is just how they say hello.
Titans for the win.