Snapchat > Instagram
I mostly use those two. Never really got into Twitter, and Facebook's useless outside of the birthday reminders (thank God for those, honestly!)
I use instagram and tumblr the most. I only use facebook for messenger.
I've never gotten into twitter and I dont know anyone that has one. It trips me out that its so popular. I see it as a celebrity thing rather than the average person. But apparently its popular.