If you need your content to be found, increasingly Google is better than Facebook
Facebook instant articles are losing to Google AMP. "Google sent 466 million more pageviews to publishers — nearly 40 percent more — than it did in January 2017. Those pageviews came predominantly from mobile and AMP. Meanwhile, Facebook sent 200 million fewer, or 20 percent less." - Facebook could easily utilize its pricing power to give Google a run for its money but seems happy with its more lucrative ads in the newsfeed. It could also give priority to publishers when a search term is entered by users, a predominant way Google is making AMP articles work, but it chooses not to do so. If you are a publisher who wants to monetize their content it increasingly seems you should prefer Google.