Written by Ishida Sui, this series is the one that has stood out the most to me. The story revolves around the gray area in between the concepts of good and evil, with the recurring themes of the monsters both within and surrounding us.
The Art both in the manga and out of it is simply astounding. The art in the beginning starts off fairly simplistic, as Ishida drew it all himself. But as it goes on it evolves into a beautifully drawn piece of art. I personally wasn't impressed with the anime adaptation, having first read the manga, but it has its moments. And for all of you who have read/watched it, feast upon my memes!