[tannhaeuser]

The requirements listed for a "modern JavaScript framework" are completely generic. Of course, if you include requirements such as "declarative" and "broad mindshare", you can only arrive at React, Angular, or Vue - at the moment that is.

Is this for internal Wikimedia apps or intended as a long-term replacement for Wikipedia/MediaWiki? If the latter, a prime requirement surely would be to support MediaWiki markup wouldn't it?

The problem with this kind of assessment starts with the deliberate decision that you need a JavaScript "framework" at all in the first place (that isn't just motivated by a junior dev seeking to pad his/her resume). Going from there, since you desperately want to persuade yourself that today's frontend landscape isn't just a result of big media influence (Fb, Google), you necessarily choose Vue (I know several companies who settled on Vue because they couldn't stand the React hype).

In other words, decisions for a particular JavaScript framework are as generational as ever, and the hope for a choice with a long-term perspective is futile, because a new generation of webdevs will soon re-invent their generation's framework since maintaining daddy-o's web framework isn't fun, and because every developer wants to carve out a niche for creativity.