Which of these apps is more convenient to discuss something? I tried Twitter, but the size of comment is restricted, therefore it left me feel that I didn't tell everything I wanted.
As for Facebook, at least in my social circle, it turned to a place for promotion of services, yoga classes, workshops, art for sale and so on. And a lot of people have made Facebook a place for sharing there private issues and thus attracting attention, making some drama around them. They talk about there divorces and marriages like about very deep life experiences and that they realized a lot from it and got very deep insights... Recently I reduced my Facebook friends three times. Just got tired of people attracting attention and make their psychological issues something meaningful and unique.
I like Instagram. I follow there some celebrities and football players that I like and comment their posts. Even though, it might be stupid from someone's point of veiw:)