Material and finish with best heat conduction

Hi there,
I’m wondering what metal like copper, silver, aluminum, brass or bronze has the best heat conductivity and contact heat transfer in combination with the material dependent finishes. E.g. does the PU coating block the otherwise high conductivity of copper/brass/bronze? Is it possible to get red/yellow gold coating without PU, as it seems like the best choice for heat+contact transfer, still being a bit cheaper than silver (and gold)
Thanks!