I hate all three. I understand some of the decisions but other ones are frustrating.
Let me explain what I used to do. What I used to do, is take advantage of the fact that firefox profiles are completely separate instances of firefox, each with their own settings and extensions. I would run my personal profile with highly aggressive and experimental settings, because I was ok with it crashing if it meant I learned interesting things. On the other hand, the profiles related to schoolwork and other more important tasks would be defaults, so they would be much more stable. I no longer consider this a necessary feature, but it was fun to play with.
The other big reason why I relied on the old profiles, is because they have separate cookies and whatnot, which is useful for when I want to have an account for each profile. Although Google happily lets you sign into multiple accounts from the same browser, Microsoft, Discord, and many other apps do not, and force you to sign out before signing in again.
But this is painful. Things never open in the profile I want them to by default, which is annoying. In theory, and I am considering doing this, the way to fix it is by creating app menu shortcuts for each profile, and then having them be the apps I select whenever I want to open a website link or file (with no default profile/app set, so I just select every time).
In addition to that, each profile had to have it's own mozilla account for syncing, which was annoying.
Containers seemed like a nice in between. I could use a single mozilla account for sync, but have seperate microsoft or other accounts on the same browser instance.
Except nope, they actually suck and don't work like that. I can't decide a window is dedicated to a container, so all tabs from xyz site will open in that container and give me that account. It constantly prompts me and it's painful and the UX for what I'm trying to do is miserable.
Containers seem designed more for isolating cookies between two different sites, rather than hiding instances of sites from themselves. Like the original version was a "facebook container", which would hide the facebook cookies from other sites, but I don't want that. I want to be able to log into multiple facebook accounts (hypothetically, I don't actually have a single facebook account but you get the idea).
The new profiles, if you've heard of them, somehow manage to combine the worst of both worlds. Firstly they are an entirely separate system and can't be managed by the second profile system. But they exist within a single one of the old profiles, meaning I can't do tricks with desktop shortcuts to make apps open in one profile or the other. But at the same time, despite existing within one profile, they each require seperate Mozilla accounts for sync.
I am very frustrated, but als resetting up my system so I am considering what to do. I am probably going to continue with profiles, but add app menu shortcuts for them.
Any better ideas?
For whatever reason, new/blank tabs don't show up as attached to a container, but once you actually load something in it, it should be bound to the container if you set that option I mentioned.
I can try to post some screenshots later if you're still having trouble.
Aha! That seems to be it. The tabs in a window do get automatically assigned to a container.
Except this only seems to work on one window at once. It's a bit painful to create tab groups for every relevant window, for task sets that I want to isolate to the same container (like when I am working on two classes at once).
Also, is it possible to get links that are opened from outsie firefox to open in the correct container?
I think links opened from outside firefox will open in whatever the active tab group is currently set to. You could also play around with the pattern matching if there are sites you always want to catch in a specific group/container, but like I said I don't use that feature personally.
I usually just use a single firefox window for most of my browsing tasks and switch groups inside it as needed. Groups are persistent between sessions, and I usually keep a few groups around for different projects as I work on them -- you could try setting up a group for each class you're taking and switch between them quickly with the menu (or set up hotkeys, if you prefer).
You can open two windows and change groups in the second window independently, but I don't have much experience with running things like that, so not sure what quirks you'll run into.