Heh heh. You know, I always hear about Sigh being so original and different, and I like 'em, but "original and different" are not words I would EVER apply to them. Their main fault is their generic-metal sound. And lest I think that I've only heard unoriginal songs, well, they sounded the same when I saw them live last month.
Is "Imaginary Sonicscape" a radical departure from their previous efforts? How is it original and different?
My vote would be for Maudlin of the Well or Khanate. Simply by virtue of their songwriting, I'd go with MOTW, although Khanate's overarching concept of atmosphere is pretty original.