Go For MERN/MEAN its the trend now.. In future there will be more job opening for them. Even currently Software Engineer getting 80+ and SSE starts with 150k and can go up to 250k with experience.
But learning php, .net, java at least in normal level is worth coz companies like those who have extra language knowledge as well.
But not sure that React can survive for next 5.6 years with current JS Framework trends, 3years before, it's all about angular,Ionic, but now it's all abut react,react native
things like Redux is hard to understand, learning curve is high, not sure worth of learning it. But currently i'm learning MERN stack 

