If you have time, implement the same application using multiple solutions. That will teach you the most about their capabilities. I would pick Alt, Redux, and MobX to study myself. I expect particularly MobX will gain popularity this year, but as you know these things change fast.
Even though there are certain similarities between the approaches, they diverge somewhat on certain aspects. Redux is great in that it is very explicit. It's like driving with manual. MobX is more like automatic transmission. Alt is an older solution, but it's good to be aware of as the API is quite tidy.
To answer your question, study all three, and then some. There will be more to study. I'm certain of that.