One thing I like React is it is plain javascript.

Therefore I can use coffeescript to describe the component:

    {div, p, ul, li} = React.DOM
    ...
    render: ->
      div className: 'foo',
        p className: 'bar', 'blabla'
        p className: 'bar', 'blabla'
        ul className: 'somelist',
          @state.items.map (x) -> li key: x.id, x.content
            

If Riot.js uses a custom parser, it may not be able to do this.