Aurelia

Aurelia is a new JavaScript framework created by one of the team members of Angular 2 project. Different from Angular, Aurelia is composed of a collection of libraries that work together using well-defined interfaces so that it’s completely modular. This means that a web application only needs to include the dependencies that it needs, not the complete bundle.

Aurelia's APIs are carefully designed to be consumed naturally by both today's and tomorrow's most useful web programming languages. Aurelia supports ES5, ES2015, ES2016, and Typescript, which are very helpful and give you high flexibility.

Furthermore, writing web applications using ES6 is not a new thing. In fact, there are many solutions out there that can allow you to write Angular apps using ES6 (you need to configure it manually and it's not included in the default Angular configuration).

You don't need to worry about special framework concepts or syntax; Aurelia is a convention over configuration framework, encouraging you to use good practices when developing applications, and it allows the developers to focus only on business code.