Earlier quoted context omitted.
I would suggest Polymer. Web Standards based - has comprehensive library of elements and polymer itself is a tiny library. I've had very good experience with it - if you know html/JS you will feel at home. As for being "feature complete" - it has probably best implementation of material design elements and you can find a ton of other element on https://www.webcomponents.org/ . It is also interoperable with other solu…
Polymer is built for the world without Vue.js or React. They are slow and heavy weight compared to very very optimized DOM operations done by Vue.js or React. I think the time for Polymer is gone, and it is better to forget that it exists.
If angular 1.5 was OK for thousands of devs over recent years then Polymer that is comparable to ng2 or react is more then enough.
Not to mention that for a world without polymer - some of biggest enterprises in the world are betting on it (and I don't mean just google here).