Silver is the best conductor, but it costs lots of $$$.
Copper is the next best conductor. Silver is about 6% better than copper.
What I'm waiting for is carbon nanotube room temperature superconductors.
Talking about carbon nanotubes, I've heard that heatsinks made of carbon nanotubes fare better than Alu heatsinks. Will castle be using carbon heatsinks on escs one day?