I'm just using Mozilla's Multi-Account Containers extension. In my work's infinite wisdom I have a total of five "single sign on" accounts. So I have different containers for each account so I avoid the endless "which account would you like to use" and "this account doesn't have access to this resource".
The extension allows me to set specific domains to always open in container X. That covers 90℅ of my use cases. Some sites I need to use different accounts with and for that I have to select which one to use each time.