I never had a Twitter, but had a FB for sometime as one of my old girlfriends set one up for me. I had it for about 7-8 years and then finally deactivated it after college in 2014 as I could see the writing on the wall.
While it can be used for businesses and social groups, staying in contact with friends who live far away, and group messaging, ect. I find it to be the purist form of narcissisism from an individual standpoint. "Look at me, look at me, my life is so great, or my life is so crappy, look at me". Its basically just a platform to show everyone a perception of yourself that you want them to see. It's also the easiest way to spy on people and see what they are up to, you never know who is looking at you. You can write some stupid crap being angry and it can prevent you from getting jobs, it can ruin friendships, it can make people think of you differently than when they saw you in person. You can write something political and lose half of your "friends", or whatever. I also found that most of the time, only your newest friend requests would see your posts, people who you aren't that close with, but just friend requested you, will see everything you say, but a friend you've had on there for a 3 years you may never see their posts or they see yours. From college I had a lot of girl friends on Facebook and just their constant drama was enough for me. I realized that I didn't need it anymore. I didn't need people to see everything I'm doing in my life, didn't care about theirs either anymore. I realized that It would be better for people to wonder what the heck I'm doing and where I went, rather than me show them on Facebook.
When I finally left Facebook. It was a great change. I felt a lot more free to my self, I didn't feel like I had to prove anything or try for some status of who has the most friends, what can I say today to get a bunch of likes? That is the narcissistic side that is ruining people. "My group says I'm right therefore you are wrong". Ever since I left Facebook my life has been so much better and when I found my girlfriend who became my wife, she didn't have one either and we live our own lives together without any stupid drama or worrying about "our look" or dealing with idiots on Facebook. I'd highly recommend canceling it. Screw Mark Zuckerberg and his spying apparatus anyway.