Whether Vue or React is a more "complex" I think depends on how in depth you want to understand it. I could see that Vue is less complex to use, at least superficially, but I think it's way harder to understand.

When I look at the guide and I see stuff like this:

    <div id="app-2">
      <span v-bind:title="message">
        Hover your mouse over me for a few seconds
        to see my dynamically bound title!
      </span>
    </div>

I get immediately queasy about what Vue is doing. Does it parse the HTML? How exactly does scoping work? What sort of special classes and expressions can I put in the span, and in what manner will they be evaluated?

In contrast, React is a JS library, and works like any other. JSX is weird for the first minute, but it's a very light transformation to the underlying JS, to the point where when I write it I can mentally see what JS functions I'm invoking, which therefore helps me understand all those things I mentioned before like scoping rules, what this will refer to, etc.