What is the best way to pass an Excel rage to a user defined function?

I pass a big range from an Excel spreadsheet to the parameter ExcelRange of a user defined function (UDF) written in VBA.

1. I can declare the parameter ExcelRange As Range and then convert it to Variant:
   Dim VariantArray As Variant
   VariantArray = ExcelRange.Value2

or

2. I can directly declare the parameter ExcelRange of the UDF as Variant.

In either case, inside a loop, I will convert each element of VariantArray to a Double variable.

Which is more efficient, 1. or 2.?