Which RDMS for Tableau connections

Question

Finally, we're switching from Excel and.csv files to databases. Most of my Tableau files are currently attached to large.csv files (.twbx).

In Tableau, are there any performance differences between PostgreSQL and MySQL? If you were to start over, which would you choose?

I'm currently using pandas to join files and generate a new.csv file depending on the join.

(For example, I take a 10 million row file, remove duplicates, and construct a main key, then merge it with a 5 million row file using the same key, then export the resulting 'Consolidated' file to.csv and connect it to Tableau.) The joins can be difficult at times, including dates or times and several columns).