But with Firefox, all the UI choices are gone now, intentionally sacrificed on the altair of rewrites, UI changes, branding and some dubious security claims. You used to get the choice of vertical tabs (better on todays widescreen laptops), tree-style tabs, Buttons where you liked them, user-provided CSS customization for pages and the UI. Not anymore, all gone (they paid some lip service to some of the above concerns, but nothing relevant, and overall a massive downturn).
Now you only get the take-it-or-leave-it of one crappy and worsening Chrome clone UI.