What's wrong with vanilla React/Flux? I'm currently working on a greenfield project and I've more or less settled settled on that stack. I have immense respect for Abramov but I'm finding it hard to justify Redux when Flux works well.
That said, there's nothing wrong with vanilla flux. Just that I find redux much easier to understand and follow.
I'm among the many people who previously used vanilla flux and prefer what the Redux style brings to it.