Which question comparing two different metals is best answered through science?
which metal is easier to use?
which metal is harder to find?
which metal is less dense?
which metal is more valuable?

When two metals are being compared science the best answer that we can find using it which element is harder to find than the other one.

Which metal is harder to find?

Explanation:

The metal  which is found in abundance will be available for use as and when required but the one which is very rare in nature. It will be available list for use hence becomes more valuable. All other given properties are also important but this property is most important.