I haven't watched too many animes considered sad, but I've watched AnoHana, Angel Beats!, and Grave of the Fireflies.
The only anime scene that's ever made me cry was in AnoHana, when Menma dies.
Angel Beats! was sad, but it was more like, "Gee Otonashi, I totally shipped you with Kanade, and I feel for you, but too bad, life sucks for you.
And Grave of the Fireflies was just terrible for me. It failed to evoke anything close to feels.
The only anime scene that's ever made me cry was in AnoHana, when Menma dies.
Angel Beats! was sad, but it was more like, "Gee Otonashi, I totally shipped you with Kanade, and I feel for you, but too bad, life sucks for you.
And Grave of the Fireflies was just terrible for me. It failed to evoke anything close to feels.