Never knew about this topic. AnoHana + Angel Beats and Hare's death in Guilty Crown..

Clannad and Clannad: After Story have to be the saddest, yet most beautiful/wonderful animes ever. Normally I only tear up during sad moments, but this anime actually made me full out cry for several days =(... Every time I think about the events that happened, I can't help but feel incredibly sad. Might even be emotionally scarred, seeing as I've been losing quite a bit of sleep over it. Clannad is so closely related to real life that it's scary at times (and extraordinary), it really makes you think about the decisions that you've made, and the impact you have on society. I've definitely had a change of heart lately; this anime has made me see that my decisions aren't always the greatest and how I can change for the better and live life to its fullest potential.

Well for me one of the saddest is Full Metal Alchemist. Sometimes it can be really sad.

Hakuouki (the second season) for example T_T
Eh, though I do cry often over sad anime things, that's why I could name maaany such animes, and then you'd ask me "So..Why would you cry here? ._."