I've stayed on FB mostly for the Groups I'm in where you can get some great advice and keep up to date with things. Well run groups are a real bonus. I also use it to keep in touch and have met up with old friends and maintained countless good relationships with people. You can scroll past anything you don't like and can easily filter out and block the idiots. I find it a useful resource.
I also need to stay on as we have a Facebook page for the band I'm in.