Which of these two Nancy Drew games should I buy?

Well, if you would like it to be difficult, I would suggest the Haunting of Castle Malloy. The whole game takes place at night and you get to travel all around when there is a ''ghost" flying around. The difficulty level depends on if you pick Junior or Senior Detective. On each level it is challenging. But on the other hand, Warnings at Waverly Academy is good, too. It is not that creepy though, and it ends very quickley. Not that difficult, but I would definitaly go with the Haunting of Castle Malloy.