For Users as a web application running on Browsers?
If it is for #1,
I would go for ReactJs as the learning curve is lesser and fundamental JavaScript Concept wins over some Framework's proprietary. It means, a developer with fair knowledge of JavaScript fundamentals can develop, maintain application with ease and can resolve bugs with lesser ambiguities.
If it is for #2,
I wouldn't go for either of them simply because of the fact that, all uses DOM Diffing as the mechanism to find what has changed and update it accordingly at the Runtime. This itself cause a worry that, it is possibly not the best way to serve the fundamental of Reactive Programming.
Not upsetting the reactjs lovers(including myself) but, it is acceptable that,
There are thought processes to address this and we are already hearing the buzz like, SvelteJs. It helps doing thing at the build time than the runtime. Worth giving it a try and read about the thought of doing it differently.