The ones with the Witches actually portrays Magrat similarly to how I originally imagined her before I read the first book Wyrd Sisters - bushy red hair.
I have always been confused with their appearence because Josh Kirby kept switching it with every book. Particularly Agnes, who I believe is only seen slightly in the cover of Masquerade. I think Kirby kept getting confused between the looks of Granny and Nanny.
Well, this French artist is pretty spectacular and keeps to one style, like Kidby.