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.
It's quite complicated choosing between those social networks but to my opinion, I'd say choosing YouTube is the best option of all why because it's the world's most second platform with most visitors every month. So my option must be YouTube for sure.