Anime that have particularly well written stories?

I don't know how many of you have watched Gosick or are watching this, so I will keep spoilers out. This show has fantastic character development as well as a generally progressive story line. Within each arc is a crucial piece of information to the plot and a great sub-story. My mind was blown by the Leviathan the Alchemist Arc. Does anyone else feel this way about an anime they have watched?