Frameworks which use to make the best design.
1. Appiphony Lightning JS :
Appiphony Lighting JS(ALJS) gives harness with jQuery Library and Ember to deliver a rich UI experience to our Salesforce Lighting Design System.ALJS is implemented and maintained by Appiphony.
Click here to Getting Started with ALJS.
2) Lightning Dart:
The library for implementing web applications based on the CSS framework Salesforce Lightning Design System is Lighting Dart. Here we can find CSS, icons, and fonts which are useful while implementing Web Applications.
Click here to Getting Started with Lightning Dart.