There are a lot of really good songs on Rubicon. At first, my favourite was Exile. There's something about it that just resonates with me. But then as I got familiar with the album, my favourite has turned to Protection. ♥ I love everything about it! And the surprise of growls was nice. It took me a few spins to even realize they were there.. haha.
My 3rd favourite would have to be Illumination.