>>34216026Arguably this.
There's at least a clear resolution to BW2 girl, and we know that it wasn't really cold-blooded murder because it was previously established that Darkrai doesn't do that shit on purpose.
XY Girl was super vague and was just the sort of thing that gets wannabe YouTubers talking.
This sidequest was tame in that most of the horror is actually a bunch of misunderstandings, but the little girl's true situation is never fully revealed, and we can't tell if the Drifloon accompanying her is an innocent bystander or a murderer. This makes it significantly creepier.