All right, so I've chosen Tom Felton as my Moist von Lipwig. He's handsome but without any distinguishing features, he has the perfect smile for Moist, and when his hair is sandy brown/dirty blonde, rather than bleached for Malfoy, he has the color hair that I've always imagined Moist with. Also, he's pretty very good looking. Pic spam, who ask? Well, why not.
The last two photos and the last two gifs are really what makes him look like Moist to me. Also, I've picked Dianna Agron as my Sacharissa Cripslock. A gif in case you're not familiar with her. She's gorgeous and very, very sweet.