Who, in The Lord of the Rings, was the most effective liar?

[Raynor]

Originally Posted by Eönwë

I vote Saron because he made all the Numenoreans evil and take part in human sacrifice.

Not all the Numenoreans turned evil - some of them remained faithful and due to them the kingdoms of Gondor and Arnor were later established after the Akallabeth.

he created the dwarven rings, as well as the ones for men, and they both at first accepted them.

The elves made all the power rings, admittedly under his guidance. As for the rings being accepted, as said before: it is not a fact that he was the one who convinced them in person.