Facebook and Instagram.
10 years ago they were very helpful for keeping up with friends I didn't see very often. Now, Facebook is full of sponsored posts and politics rather than the personal updates I want; and the Instagram feed has more posts from people I don't follow than from people I do.
I stepped away from both a year ago. In the main, I don't miss them. The unfortunate part is that Facebook is the only place local community stuff is posted, so I can't quit entirely. But I no longer have the app on my phone; I just open it in Firefox when I need to look do a specific thing.