Animation Appreciation Thread #5

The Sakuga Wiki [JP] - http://www18.atwiki.jp/sakuga/
ANN Database - http://www.animenewsnetwork.com/encyclopedia/

Animation Blogs [Eng]:
http://www.pelleas.net/aniTOP/
http://aninomiyako.wordpress.com/

Animation Twitters [Eng]:
http://twitter.com/Duune99
http://twitter.com/kyouray
http://twitter.com/catsuka
http://twitter.com/raito_kun
http://twitter.com/americopun [JP]
https://twitter.com/honnyaku_blog [JP/Eng]

Animation Tumblrs:
http://cammadanar.tumblr.com/
http://unkoer.tumblr.com/ [JP]
http://americopun.tumblr.com/ [JP]
http://ganasu.tumblr.com/ [JP]

Previous threads:
#1 http://dis.4chan.org/read/anime/1291816034
#2 http://dis.4chan.org/read/anime/1314681601
#3 http://dis.4chan.org/read/anime/1325612276
#4 http://dis.4chan.org/read/anime/1336754773

So, I don't know if this question ever popped up in the previous threads, but what do you guys think are the anime series with the best animation ever?