From that list I prefer YouTube, but is it really social media? It is for posting vids - the "social" aspect is the weakest part of the platform. So for social media I voted Facebook. It is the easiest way to keep up with friends & family back in the old country, and has built in video chat.
I find Instagram & Twitter to be just truncated copies of Facebook. IG is for pics, twit is for short status updates. I use IG to advertise my YT, and have never found a use for twitter.