Meisel changes his favorites in the blink of an eye... And I agree that Valentino likes Doutzen, but I think for Pierpaolo she's indifferent.
Yes, Doutzen has never been anyone's favorite, but I think Valentino was the designer who most valued her and gave her every opportunity (opened, closed, led and campaign), a real muse for him. Although she never had a period of being that was everywhere, she had constant work and clear since always she fell in the taste of people since in 2005 she was elected model of the year by readers of Vogue and VS gave a lot of popularity to her (she made her name and kept it popular and I think that's why she gets more work than many models from the same time of it can't), I think she is well liked by the other models and have a good relationship with people who work in fashion despite not being the favorite, so she is always doing something here or there, and of course because her natural and classic beauty!