I think Vue has potential, because it took the best from react + angular, has reactivity by default, and it's much easier to get starting with in my opinion.
Also vue has good solutions for state management, as a beginner one doesn't need to think about redux vs mobx, or other flux implementations, just goes with vuex, and routing which I think it's a mess in react world while vue provides a good library that will stay in sync with the view library.
In terms of users, react is probably a clear winner in the western countries, but I think vue is more popular in china and other asian countries + laravel community, that's why I think it's bad to talk numbers.
I am of course a little biased so I want to add that I hate the hype around a framework or another. There is place for every framework with different ideas/ implementations /size and performance.
I hope to see mithril grow too.