Material Design Lite is the framework that is most true to MD guidelines and requires less code to implement. That being said, it is still early in development.
I tried Polymer for 6 months ago. It looked, but it was every early, and I was developing with Angular. Later, I switch to React which is a better fit for me than Angular. But I still wanted MD, so I tried both Material_UI and Materialize. Material-UI is a React implementation of MD and Materialize uses jQuery. I quickly discarded them.
MDL is as the name says very small and mostly built with CSS. You can customize the CSS classes easy, if you need to. I like BEM. It might be difficult for some to use, but long-term in large production apps, it is great for easy maintenance.
I encourage everyone that like MD to try it out and file issue requests for bugs or feature requests if you are missing something.
I tried Polymer for 6 months ago. It looked, but it was every early, and I was developing with Angular. Later, I switch to React which is a better fit for me than Angular. But I still wanted MD, so I tried both Material_UI and Materialize. Material-UI is a React implementation of MD and Materialize uses jQuery. I quickly discarded them. MDL is as the name says very small and mostly built with CSS. You can customize the CSS classes easy, if you need to. I like BEM. It might be difficult for some to use, but long-term in large production apps, it is great for easy maintenance.
I encourage everyone that like MD to try it out and file issue requests for bugs or feature requests if you are missing something.