I know everyone has their reservations about Microsoft and their developer ecosystem, but WinJS really is a delight to use, at least in my limited experience. A WinJS app is really just a zip of a bunch of JS (using WinJS's nice APIs for fancy stuff), CSS, and HTML, so most web developers who are used to the modern tool chain should be pretty comfortable with it. And yes, you can supposedly use it alongside Backbone/Angular/whatever. Worth a closer look.