The daughter is prettier.
Well, I don't think that Marie Gabrielle's looks are comparable with those of her mother Marie José. The daughter was a blond with blue eyes and Marie José inherited the dark features of her parents.
In my opinion Marie Gabrielle was a pretty girl and young woman, but her fragile health and the loss of her children made her look unhappy, sad and exhausted.
Anyway, she was the most beautiful daughter of Carl Theodor. Amélie looked a lot like her mother Sophie of Saxony, Sophie was quite featureless and Elisabeth had that longish face I will never get used to.
I have always prefered Marie José - she's one of my all time favourites. :-)