This chart shows each technology’s satisfaction ratio over its total usage.
Additionally, technologies that have an interest ratio (percentage of non-users interested in learning it) over 50% are displayed as “on fire”.
For the longest time CoffeeScript was the lone proponent of that strategy, but today it's been overtaken by ES6 and its follow-ups, TypeScript, Flow, and even languages with very different syntaxes such as Elm and Reason.
But until that time, the two big winners here are ES6 and TypeScript. Keep an eye out on Reason as well, which has Facebook's support and boasts both very high satisfaction and interest rates.