Chanel/Lagerfeld tend to pick their ambassadors much better I think. Audrey Tautou, Keira Knightly, Kristen Stewart, Marine Vatch, Astrid Berges-Frisbey, Anna Mouglalis... They all seem to fit the brand very well and have a spark. With the exception of Lily-Rose Depp - but I doubt they'd have spontaneously chosen her if it wasn't for her mum.
With Dior and LV their choices seem more random. They picked Lawrence because she's the biggest young actress but she's the opposite of fashion and glamour for me (I still remember her saying in an interview that she never washes her hands after using the toilets - I find her tendency to overshare to be relatable off-putting, although she has been more reserved lately).
Even Selena Gomez with LV was very random and very "let's target the millennials".
As for Alicia, she was supposed to be the next big thing but it hasn't happened (yet), and although she's very pretty, her ads tend to be lifeless.
I'm not sure who I'd replace them with though.