Current: Power BI by Microsoft
Previous: Tableau, BrightGauge, SSRS
I'm going hot and heavy into Power BI right now.
I've used Tableau, and while it's great, the pricing model didn't fit with our needs.
BrightGauge is fantastic for mom and pop, so to speak, but you'll bump into walls really quickly.
SQL Server OLTP DBs
SQL Server data warehouse with custom C# ETL tools to pull in OLTP and API data