The short version:
CoffeeScript if you much prefer Python or Ruby-style syntax and you're uncomfortable with JS's uncomplicated approach to OOP
JSX if it's just dynamic types that horrify you and you're uncomfortable with JS's uncomplicated approach to OOP
Dart if like 99% of Google's Stanford grads, anything that doesn't look a lot more like Java and working without an IDE horrifies you and you're uncomfortable with JS's uncomplicated approach to OOP
...and finally Fantom if you've actually bothered to learn both kinds of languages, C# AND Java but can't be bothered to learn anything else and definitely can't be bothered to learn JS's uncomplicated approach to OOP
Obnoxious? Yes, okay, a little. Okay, maybe a lot. But how can we answer this question? I don't know what you like or find easy and that's basically the list of "problems" these down-compiled-to-js languages attempt to solve.