One thing I've found really really useful is handling multiple google users over multiple google sites.

I want youtube & google music to only use my personal account, so I never need to switch accounts, so google music and youtube open in their own container where only my personal account is logged in.

I want gmail and calendar to use my work account, so they open in the default container and automatically use my work google user.

I know that you can set your default google account by logging into it first, but I specifically don't want one default, I want different defaults for different google services, and that use case is handled beautifully by containers.

Anything where you have to log into an account with a secondary identity. So I have one for my work account Azure as it’s a different Microsoft account, one for work Google API projects as it’s a different Google account, etc. Used to have to use different browsers (even IE, ugh) but now there’s no need. I love containers (longtime Nightly user) but the UI is hard to get right and even harder to make intuitive, so I’m not surprised they made it an extension.

I wonder about this as well. What are people finding is the best use of the default container - what opens as a new tab?

Do you keep that your personal container, and opt-in to other containers like work, shopping, etc.

Or do you use the default container as your most used type - perhaps work - and opt-in to personal/shopping containers as needed?

Keep the default container blank and try to always open up a specific container?

It's useful for handling sites with really long login flows, and multiple accounts, so I use them as the exception, rather than the rule.

Eg: AWS I have a work and personal account, and their login flow sucks, but the work and personal containers handle this situation easily.

I would have a container for each of my major social network / email accounts, like one container for each of twitter, Google and Facebook.

Yes, and then do your browsing in non-containers so that browsing is isolated from the account logins, and vice versa.

Or use the multi-account container addon: Which will get you a new container, in a new tab with 1 click.

https://github.com/mozilla/multi-account-containers/#readme