Because at the end, it depends on the watch.
A Cabaret ? Pink gold is my fav color !
A Saxonia ? The Pink Gold Grey dial is my fav combo !
1815 chronograph ? White Gold !
Lange 1 ? Platinum !
Richard Lange ? Platinum !
Datograph ? Pink gold !
But with the Zeitwerk, no doubt ! White gold without any hesitation ! It is not due to the material but due to the dial.

Fr.Xavier