Managing isolated cookie profiles is the real cornerstone of a web browser because it’s a feature that depend on the capabilities of the underlying browser engine but UI wise it touches things like open tabs, syncing and bookmark management.
Here’s my State of the Browsers report:
If you don’t need vertical tabs and advanced grouping, in my opinion Safari is pretty good managing different profiles, with the special touch that the Favorites bar will change depending on the profile using a special location in the common bookmarks tree which is shared across profiles and is synced via iCloud. The UI for selecting windows and profiles is totally absurd but coupled with some extension magic makes it very simple to create Profiles on demand.
The other Webkit browser, Orion, has super powerful nested vertical tabs and also has profiles but they do not share bookmarks at all and profiles other than the default one will not sync through iCloud. So if you create bookmarks in your non-default profiles you will not see them in other computers.
In Chromium based browsers having a different isolated profile and sharing tabs and bookmarks across devices requires a syncing email address which makes it less useful as usually one only has a work email address. Arc did manage to overcome this in a very cool way with a single email address for syncing and giving you the capability to associate the “Workspace” with the “Profile”. Also The Browser Company created the perfect Raycast extension for Arc.
Vivaldi is another uber-browser but as far as I know their Workspaces are just collections of tabs, they do not have isolated cookies. And the same happens with Edge – all Workspaces share the same cookies and bookmarks so they’re really only tab collections. Syncing workspaces in Edge works just fine, though, so you can use them to organize your tabs.
Firefox has this capability but it’s in the form of Firefox Containers and to be fair it can be confusing as hell (just try to undo selecting “Open this tab always in this container” by error), but at least only requires one single email address for syncing like Arc or Safari. Zen, basically being Firefox with a lot of custom plugins to make it look like Arc, will get there eventually and still has some minor edges but it’s good for day to day work. But it’s not yet as polished as Arc.
In the meantime, Ladybird is still cooking and it seems it will take some time to see the direction it takes in terms of profile management.