Which wire is best for electricity either copper or aluminium?

That depends on the application you have in mind. Copper is 'best' for conducting

electric current from place to place without loss. Aluminum is 'best' for keeping cost of installations down or where weight of the conductor is a factor. A larger conductor size has to be used when using aluminum wire to carry the same current as a copper wire.

Aluminum also has some issues backing out of connectors so its important to make sure the connectors are tight. The current is actually carried on the surface of the conductor, which is why stranded wire is better than solid wire, more surface area, but more expensive. Hence aluminum has been substituted for copper. Some applications will use steel wire and "flash coat" the steel wire with copper, so the surface is copper the base is steel.