I tried PatternLab out for a D7 site I was/am working on… hacked together a Twig engine for rendering the templates using a JSON schema that I had generated from a bunch of Paragraphs block types, and that worked pretty well, but we outgrew it pretty quickly as our needs grew beyond a few simple fields. Have you used it much?
To be honest I haven’t tried it with D8, beyond a quick setup & demo that I later left behind — I haven’t actually been able to use D8 for any projects yet, due to some issues I’ve had with usability for content editors as well as performance (which may have since been resolved) and the fact that so many of the contrib modules on which I’ve come to depend aren’t yet stable yet. If I had 48 hours in the day I would love to help out more to get those upgraded, but alas I’ve got my own startup to focus on.
React, and the Node community in general, has really impressed me with the speed at which issues are resolved and technologies integrated. My team started with a small set of “atoms” and “molecules”, and it quickly grew to cover all our use cases with respect to UI. It seems naturally suited to that, since the component model is baked right in, where the borders between atoms, modules, organisms, etc are clearly demarcated and the pieces belonging to each of those components fit neatly inside.