Um it depends on which one you use the most. In my case it's Facebook, because it's the on I use the most. I only have 3 pictures of me on Insta and rarely use snapchat. But if I used them all equally I would have to say that instagram is the leat intimate and Snapshat the most intimate.
I guess snapchat. I've heard of it though I have no idea what your supposed to do on it. Along with Instagram, no idea what your supposed to do with it. All I can picture is you add pictures and that's it.
Definitely snapchat. Facebook use has decline now and days, so people rarely post on there. It's not a big deal. Instagram, well, I would let anyone follow me on Instagram. Snapchat, you get to see what they're up to almost everyday and send flirtatious snaps.