Backbone never got really popular here (Sweden). I still see some legacy apps running Angular but React took over from jQuery quite fast in 2015 or so. What I have noticed thouhg is that people who like MVC-frameworks tend to like using libraries similar to Vue and those who have more of an application approach to web apps tend to like React. Personally I think I got a bad first impression from Vue and have had a hard time trying to get to like it (I know it is popular). I think libraries such as Svelte and dev environments similar to Snowpack will gain traction the coming years. Focus on Developer Experience and doing the heavy lifting in the dev environment.