Hugging face: https://huggingface.co/datasets
Microsoft Research Data Set: https://www.microsoft.com/en-us/research/tools/?
Azure Open Data: https://azure.microsoft.com/en-us/products/open-datasets#content-card-vertical-oc7603
Amazon Data Set: https://registry.opendata.aws/
Google DataSet search: https://datasetsearch.research.google.com/
Pew Research Center posts (lots of survey data and other): https://www.pewresearch.org/tools-and-resources/
Paperswithcode- the research papers are shared with code repo, often with datasets too: https://paperswithcode.com/