Facebook due to how obsessive some people can be with using it. Instagram a close second. I mean I'll use those sites occasionally to creep on someone or look up something, but when you're out for coffee or lunch with someone and they're just staring and scrolling through those its like oh my god :O :O :O
at least with like Twitter (not that I use it) people are limited on how much they can say in one post so I feel like it prevents some people from being quite so obsessive. could be wrong about that though, maybe people just make up for it in the quantity of posts haha







