There are many, many great React starter kits, but this one is mine. It includes the standard client-side libraries I would use on any new project: React, Moment, Lodash, npm, Babel (for ES6 support), Webpack, and ESLint. It also includes the ESLint rules I use for enforcing best practices when writing code using React/JSX, ES6, and Lodash. It also includes my standard Webpack config, which has auto-reloading, Babel transpilation, and CSS modules. It also uses npm as a build script (interfacing with webpack, etc.). To see a list of commands: npm run.
This repo uses ESLint, with rules defined in .eslintrc. It includes best practices for ES6, React, and Lodash. npm run lint will check code.
There many IDE integrations for ESLint, but the recommended one for Sublime Text is SublimeLinter with the eslint plugin.
This repo uses Babel to convert ES6/ES2015 code to ES5, which can be run in all browsers. It's converted via Webpack, either on the fly with a dev server (npm start), or during a build step (npm run build).
Hint: ES6 syntax highlighting in Sublime Text 3.
webpack.config.js is in a tooling folder. This is where karma.config.js would also go.