Tableau is perfectly refined and offers much more flexibility when it comes to precise, fast and intuitive data exploration. Tableau’s functionality from an end-user perspective is far greater than in competitive products, especially in terms of visualization methods, data sources, prediction, inside analytics and data presenting. Finally, what’s important in Big Data Era, Tableau deals smooth with loading and processing really large datasets.
Power BI is developing quickly and they’re closing the small gaps in their functionality extremely fast, but it’s still less powerful than Tableau when it comes to usability and number of functionalities. Power BI is especially suitable for creating and displaying basic dashboards and reports, but if you are going to spend more than an hour or two per day using it, you might want to go with Tableau. It’s great advantage is integration with MS Office, but similar to the flag Microsoft product, it has problems with large datasets.