Experiments with magnets and conductors

Resistivity of materials

metal resistivity,
silver 14.71
copper 15.80
gold 20.11
aluminum 25.00
zinc 54.55
iron 87.10
lead 193.00
mercury 983.96

So, silver is the best conductor, at least at room temperature.  (At very low temperatures, lead and mercury become superconductors where their resistivity becomes 0.00!)  Copper is close to silver, and is much less expensive.  Aluminum is not far behind, and is less expensive than copper.