I always tear up during one of the last episodes of the first season of Ghost in the Shell. The following spoiler contains info and spoilers for both seasons, so be warned.
I can't help crying when I watch the Tachikomas sacrifice themselves. Even in 2nd Gig, when they REALLY die, I still think the first time was the most emotional, perhaps because the viewer has no idea whether their deaths were meaningless or not. The 2nd time, it's pretty much a sure thing they're going to save everyone.