Before ES6, I was on the CoffeeScript road.
I voted ES6 since it's going to be a standard anyway in the future -- however, out of curiosity: why not TypeScript?
Why not ES5 as an option? ES6 support is still weird and requires adding transpilation to your pipeline. Coffeescript also means transpiliation, and also means using a small niche of JS tools available.
What are the specific problems that you're looking to solve with ES6? Promises are weird when you actually get into them, and async/await is still a ways off from real support. Iterators/yield are awesome, but support in browsers is missing (Except for FF). The other stuff is... nice? I guess? But not real problems that can't be solved in a nice functional way with ES5 code.
Why use a new tool that is still changing when an old tool that is very well tested still works great?
Matan Yedayev
Full stack developer
I voted ES6, but actually - go for TypeScript.