I've been wrestling with Facebook for a while. Not just its continued erosion of privacy in search of ever increasing ad revenue, but also the value of its service. When I somewhat reluctantly returned to Facebook a few years ago it was due to a number of events being organised (irritatingly) almost exclusively by Facebook groups and events. It was at least moderately useful. I can't remember the last time that Facebook provided me with social purpose that was of meaningful quality; I certainly havent had an event invite in the last eighteen months. I don't really feel that this initial sliver of purpose has been replaced by anything worthwhile for the most part; I have however gotten into a few great discussions and made a few friends on the way (which I appreciate) but I don't feel this has occured with a frequency in excess of other channels.
Facebook Messenger is Facebook's most insidious little hook. For some of my friends it has entirely dominated communication; presumably because of all the cross-platform message apps it is the one with the greatest reach. You can even use it to get in touch with people that aren't your friends (which I guess could be super useful, even if it is potentially super invasive). I have acquaintances for whom my primary method of contact is Facebook Messenger and this poses an issue when I consider reduced or abandoned use of the service. Of course this is all under the shadow of Facebook's agressive message scanning, which ensures that none of your correspondence is private, and that it can be accessed by the authorities with a court order. I'd rather be using iMessage with it's end-to-end encryption.
I don't see a clear alternative or replacement for Facebook; at least no alternative that doesn't or won't suffer from the same long-term issues. I'm considering going through my friends list and exchanging current contact details (good old e-mail and phone numbers) and then permanently deleting my Facebook account. I've been half considering this probably for the last twelve months, and it's probably time to shake the nagging doubt and get on with it.