I first started by writing a Phaser boilerplate using ES6 and Webpack. However, the thing missing was simple asset loading through Webpack, so I wrote a new plugin to facilitate that along with some more advanced features like compressed textures and retina graphics. Just define your asset manifest file, add the plugin and you are done.
Github/Docs | NPM
Load all game assets in parallel.
Load images, spritesheets, atlases, audio, bitmap fonts and web fonts.
Integrated with Webpack for automatic cache-busting.
Supports all filetypes.
Supports asset postfix for retina support ('@2x', '@3x', etc).
Supports automatic loading of compressed textures (PVRTC, S3TC, ETC1).