All of the ones that spring to mind are from family movies, so I'll spoiler them.
Spoiler:
Just... the saddest song in a Disney movie.
(the opening obviously gets a lot of attention and rightly so, but this scene in particular always gets me)
These two scenes are similar really but both killed me
And finally because this pretty much was a rock to me when my parents separated:
I watched this shortly after he died and yeah I was a complete wreck at this ending.