Facebook has gone to shit long before any controversy around the CEO's political posturing. The content/spam+slop ratio is pretty dismal at this point. I am sure a lot of people are ready to jump ship, given a viable alternative for even some subset of the features that they like.

For me personally, the only features that remain at all interesting on Facebook are Marketplace, Groups and maybe Events. Does anyone still use Craigslist? It was always terrible so I don't know if there is an alternative for Marketplace but Groups and Events aren't even done that well on Facebook so that seems like a reasonable place to start as far as an MVP.