That is a great question, and it depends upon the case metal.
My choice is typically white, rather than the cream enamel Peter has used in his initial production Piccadilly watches.
I have to say though that the WG case lends itself quite well to cream enamel over the white.
Also, Peter made a steel Piccadilly with arabics on cream enamel with a red gold crown. That was a lovely combo...
I dear friend of mine owns a superb 38mm WG cased Piccadilly with cream black roman dial piece from the early days. It is stunning!