I know Firefox is late to the game with this feature, but its really useful. For me, im using it to keep a number of tabgroups always open for different aws accounts.

It brings some order to things. Before tab groups, I was having lots of container tabs mixed in with ordinary tabs all over the place and often lost track of what was where.

And its the only browser that has container tabs with tab groups. In chrome, you still share cookies across all tab groups.

I still think its the best browser, at least for my needs.