Hacker News Reader

Riot: http://riotgear.js.org/

React: There are tons of repositories for React components. http://react-toolbox.com/ might be the closest to what you are thinking. I am not familiar enough with React to make a confident recommendation.

I just wish we had more on par with the desktop-ish, enterprisey stuff that ExtJS native interfaces provide, instead of umpteen material design drop-in-a-pond animation buttons... I'd be content with a good enough datatable that's not an abandoned port from some jquery plugin...

None of these are limited to whichever tech they were initially created with, it just takes someone with the motivation to port the library-specific bits over.

e.g. for React, there are ports of Ionic, Bootstrap (the only one in this list I've actually used so far), Foundation for Apps and about 3 different implementations of Material Design, plus new UI component libraries like Belle, Elemental UI, Grommet, cf-ui, TouchstoneJS, Rebass, Pivotal UI and probably more since last time I checked.