Here is my choice for favorite villain in an anime series. Light, to me, is intelligent to the point that it's just plain frightening. A lethal combination of John Doe from the movie Seven and Keyser Soze from The Usual Suspects, Light is able to successfully manipulate others as well as predict human behavior while using the Death Note in an attempt to obtain his goal of becoming the god of his "perfect" world.
What makes Light that much more scary is the fact that he does not see himself as a villain. On the contrary, he thinks of himself as the savior of humanity and that his actions will one day be regarded as heroic.
Here is the bus jacking scene which shows Light masterfully tugging on the puppet strings. LOL. Thanks to @RosePark for his Twisted Thursdays!