I really don't watch anime as much as I used to, but it's got to be Violet Evergarden.
Fuck, that series is amazing. Nearly made me bawl like a little bitch the entire series (my tear ducts and my willpower are strong so I actually didn't, but damn, Violet Evergarden was the closest to ever eliciting such a reaction from me). Episode 10 was heavy man
Also I watched that anime after school up, two to three episodes each day, until I got to the finale, so imagine my absolute exhaustion coupled with the intense emotions in the anime kinda contributed to the tearin up a bit, haha. Wish I could erase my memory so I could rewatch Violet Evergarden from start to finish again.
Seriously I recommend everyone watch it - completely blind. Especially if you're a writer, it's a good example of how to make your audience care about your characters.
And if you're wondering - I haven't gotten down to watching the movie yet, but I'm planning to.