A vertical tab list with tab groups is infinitely better than anything Chrome offers (and is indeed how I have Edge configured on my work PC), but Tree Style Tab remains Firefox's killer feature for me.
Thankfully, Firefox's decision to integrate its vertical tabs into its existing "sidebar" feature, combined with the ability to shrink the sidebar to nothingness, means that I'm now able to completely "remove" Firefox's native tab list, leaving only Tree Style Tab.
Thankfully, Firefox's decision to integrate its vertical tabs into its existing "sidebar" feature, combined with the ability to shrink the sidebar to nothingness, means that I'm now able to completely "remove" Firefox's native tab list, leaving only Tree Style Tab.