I really don't understand the underlying complaint of your comment that the React ecosystem is in constant flux (see what I did there?)

I've been writing React SPAs for roughly two years now.

Very few things have changed. The first app I've written roughly looks like the newest one. Couple of lessons learned here and there like everywhere else.

Yes, there are many Flux libraries and different implementations. However, a decent State management solution for React is roughly 200-300 LOC. So there are many of those 200-300 LOC libraries. So what?

If it's a big project, you should spend the time to figure out what fits YOUR project and YOUR team the best.

If it's a side project, use the most popular with the best documentation and be done with it.