So copper, gold, silver, etc. are going to be good conductors of heat, but they will be limited by their melting points. Each material has a property called thermal conductivity. You can look in most heat transfer or thermodynamic books to find a listing of these numbers. Look into a heat transfer book on conduction and Fourier's law. However, you can get an idea of the heat transfer capabilities of various metals by reading textbooks or other material on the subject of conductive heat transfer or possibly radiant heat transfer.
Copper is better because it's a better conductor of heat.
The best by far is diamond. It's thermal conductivity, especially at very low temperatures, is unbelievable. Look for thermal conductivity in a physics reference book. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.