which one is the best?
That depends on your requirements and preferences.
I still prefer Excel, easy to use, supports cube formula for further calculation and many more features.
I have a sql enterprise 2014 with SSIS, SSAS, SSAS Tabular & Powerbi
Powerbi is used more for gaphical view of cubes, with olap presnted in excel
Mostly finance users so they love their excel but i have other business units who would like more analytics
I'm trying to bridge the gap between excel olap finance users and powerbi, analtical tool on top of olap or onto data warehouse
Excel Olap > ? > Powerbi or even on top of powerbi
Please help, i need to evolve and data storage to azure is not an option
Just a note: You posted the question twice, once with tag SSAS and once with tag SQL
Instead of posting twice you can it one time and add both tags.