ngComponent, ES6 classes for directives. Inspired by: https://github.com/angular/angular.js/issues/10007#issuecomment-77509179. Even more experimental version: https://gist.github.com/danharper/0ce7298d14b569ac3aa3

index-v1.js

import ngComponent from 'ngComponent'
import SayingHelloComponent from './SayingHelloComponent'

angular.module('app', [])
.directive(...ngComponent(SayingHelloComponent))

index-v2.js

import {ngBridge} from 'ngBridge'
import SayingHelloComponent from './SayingHelloComponent'

ngBridge(angular.module('app', []))
.component(SayingHelloComponent)

// using my "ngBridge" extension (https://gist.github.com/danharper/0ce7298d14b569ac3aa3)

ngComponent.js

export function ngComponent(name, component = null) {
  if ( ! component) return ngComponent(null, name)

  let ddo = component.ddo()

  let directive = () => {
    return {
      ...ddo,
      scope: ddo.bind,
      bindToController: true,
      controller: [...getInjects(components), component],
      controllerAs: ddo.name
    }
  }

  return [(name || ddo.name), directive]
}

function getInjects(func) {
  return func.ngInject ? func.ngInject() : []
}

SayingHelloComponent.js

export default class SayingHelloComponent {
  static ngInject() {
    return [] // register your dependencies here (Angular 1 style, with string names)
  }
  static ddo() {
    return {
      bind: {
        person: '@'
      },
      name: 'sayingHello', // component's name
      template: `<strong>{{sayingHello.greeting}}</strong> {{sayingHello.person}}!
                 <button ng-click="sayingHello.changeGreeting()">change greeting</button>`
    }
  }
  constructor() { // you'll get your dependencies here like usual
    this.possibleGreetings = ['hello', 'howdy', "g'day", 'hi', 'sup']
    this.changeGreeting()
  }
  changeGreeting() {
    this.greeting = rand(this.possibleGreetings)
  }
}

function rand(items) {
  return items[Math.floor(Math.random() * items.length)]
}

usage.html

<saying-hello person="Dan"></saying-hello>