A couple of anime that made me cry was for sure Air's ending and Clannad: After Story.
I will never watch that one again.Not sure if it counts since it's an anime movie, but Grave of The Fireflies from Studio Ghibli. I shed some serious tears and felt like I couldn't stop for quite a while.
I will never watch that one again.
Even hearing the name is enough to get the waterworks going.
Assassination Classroom