I’m not an expert on application authentication by any means. In general terms, I’d suggest that you want to use Microsoft login credentials if the database is internal to your organization. If you’re connecting to a SQL Server database application that is in some way exposed to the internet, then you might want to use a Gmail login. However, there are many security risks when you expose a database to the internet. In a situation like that, you might need to add additional security software like Kerberos or Azure Identity Management. For more information, try referencing this Microsoft documentation.