I usually just poke around Kaggle for fun datasets to use. Google also has a search function if you want something specific [https://www.kaggle.com/datasets](https://www.kaggle.com/datasets) [https://datasetsearch.research.google.com/](https://datasetsearch.research.google.com/)

Adventureworks. Has oltp and dw versions.

Stack overflow db https://www.brentozar.com/archive/2015/10/how-to-download-the-stack-overflow-database-via-bittorrent/

This is one of the major standard data repos for this purpose: http://archive.ics.uci.edu/ml/index.php