I personally like how it handles hundreds of tabs. No matter how many tabs I have open they remain usable size, and the compact UI theme is even more compact than Chrome.

Tab containers are useful for having multiple accounts on the same site (Gmail/Github), or isolating work or most secure sites from regular browsing. The containers are more light-weight and more general than Chrome profiles (and they don't depend on having external accounts).

Pinned tabs don't close on Command+W. It's a small thing, but I kept accidentally closing my pinned tabs in Chrome.

Chrome Dev Tools are hard to beat, although Fx is slowly catching up there, too. I don't mind launching Chrome just for web dev.