The best by far of the one's I've tried is Maas metal polish. I bought a tube 3 years ago, and I think there will still be plenty left after another 30 years! Just a small dab is all you need. Truly fantastic stuff!
This might be another clone of Simichrome, the German polish that's now out of patent.
Simichrome (or a true clone of it) is by far the best metal polish I've ever used for either alloy or plating, and I think I've tried them all over the years. The critical element is a type of diatomaceous earth that is only found in Germany.