The moment Firefox gets native vertical tabs with drag and drop grouping, I'm making the switch. But, as it stands, the vertical tabs in Edge are irreplaceable and not a single of the "workarounds" to make them possible in Firefox feel good at all.
I need drag and drop tab grouping and vertical tabs. That's it.
Edge also just introduced workspaces which feels like something I'm going to love once I get the time to mess with them.
I want to leave Edge because I want to be done with Chromium in general, but Firefox feels too behind the times for me.
As I said in my original comment, none of those workarounds feel good. They show their seams constantly. I've tried a handful of extensions and not one feels as good as or is as feature complete as what's native in Edge.
That's totally fair, too. Not everyone gets bothered by the same things.
The last set up I used was this one and what made me give up is that it is so easy to accidentally close it. I had to look through my Firefox history to find that and when I closed the history sidebar, my tab bar was gone. It's just a press of F1 to get it open, but why can't I just make it persistent? Why does it have to share the same space as so many other features in Firefox? I don't care if history wants to occupy the same space for the moment I need it, but when I'm done, go back to showing my tabs.