I guess I should go for Elfen Lied, Loveless and Serial Experiments Lain!
Elfen Lied goes from one extreme to another in a very gruesome way. The contrast is absolutely beautiful! Plus, I love it how it plays around with the taboos

and serial-killer-little-girls are absolutely cute
I'm not so much of a fan of the Loveless anime when compared to the manga, but it's still one of the best ones I've seen.. As a romance story, it's like no other. What could I call it? Experimental/alternative romance? Anyways, the story is very good and (in the manga) very multi-layered, and I love it how it's build on the characters rather than linear plot.. Plus, it's actually a yaoi-series you can take seriously
Serial Experiments Lain has a lot of depth going on. I appreciate that. Plus, the theories it's build on are disturbingly close to how I look at the world.. Anyways, I'm a sucker for philosophical theories and Lain has lots

The story is complex, emotional and multi-layered like no other.. Gotta love its mood
