Google and Facebook are completely different animals. They both make money through advertising[1], but the use cases are different. Even their algorithms have different implications. In Google's case for example, their search is like an ever improving AI, increasingly hard to overtake. And assuming search is going to continue to be a need, it may become increasingly hard for a competitor to overcome them. I do understand nothing lasts forever, but only thing is I don't see it coming yet.
Sibling comment, compares Goog with MS 10 years back. My humble submission is several people saw it coming even then. I remember reading a book called 'The Search', and also having some discussions with friends, where we felt that Google will overtake MS. But there is no such thing in the horizon, which challenges Google. And people tried - Blekko was noteworthy. DDG is also liked by hackers, but it remains to be seen in the long term.
Now talking about FB's algos (or AI). Its purely anecdotal, but till I was using FB, I found it highly irritating. Imagine if your email was trying to guess which email you like to read, rather than simple time sorted one (and brief categorization, which gmail does).
[1] This analogy of comparing Google to advertising company has become a bit tiring now as well. I think, thats their current way of making money, we should judge them by what their intrinsic value is - Search/self-driving cars/Youtube/etc. As the means may change (micro-payments via Bitcoin/etc who knows?)