In reply to mark k..

I suggested Mithril.js as an alternative in November 2015 when I filed Calypso issue #650 "Replace React with Mithril for licensing reasons" linked in the article (the one with Automattic's lawyer's comment).

I still feel Mithril.js is a great choice. But the more important decision factor is to use any vdom like Mithril, Maquette, or Inferno supporting the emerging "HyperScript" API instead of a library like Vue or Angular that emphasizes HTML-ish templating. That way, people can code their UIs entirely in standard JavaScript/TypeScript which makes maintenance and refactoring easier. And in a worst case, you can always replace the vdom backend with another that also supports the HyperScript API while most application code using that API can stay the same.

See my comment here for more details on why using the HyperScript API instead of HTML-ish templating makes sense: