I want to create a Ad hoc report, in my requirement I have complex calculation, Unit conversion, decoding of IDs, even I need to pull data from different subject area( around 5 to 6 ), which is the best place to pull data for Ad-hoc reporting Staging d

I want to create a Ad hoc report, in my requirement I have complex calculation, Unit conversion, decoding of IDs, even  I need to  pull data from different subject area( around 5 to 6 ), which is the best place to pull data for  Ad-hoc reporting Staging database or Cube. I need to develop ad hoc reporting using report builder as well as Excel Pivot table