Sadly, there is no viable alternative. I use Chrome as my second browser, I occasionally use Firefox and although they are both great browsers, they offer nothing close to Opera. No configurability whatsoever and no extra features you are accustomed to.
Why would you use Chrome, but not the potential FB Opera? Google has just as much of a stake in your information as Facebook, but that hasn't led to their browser being a privacy vulnerability.
Not really. Firefox has a minimal featureset out of the box, but extensions are allowed to do a lot more. With a few extensions you can get nifty new features and UI customizations that Opera just doesn't support.