WordPress frameworks are very useful tool for WordPress developers. It is regularly used by WordPress theme developers because it takes a very small amount of time in development. Building a new theme from scratch is really hard and needs a certain amount of time as well but this is where Framework comes into play.
FoundationPress is a starter-theme for WordPress built with Foundation 5, the most advanced responsive (mobile-first) framework in the world. The purpose of FoundationPress, is to act as a small and handy toolbox that contains the essentials needed to build any design. FoundationPress is meant to be a starting point, not the final product.
Redux is a simple, truly extensible and fully responsive options framework for WordPress themes and plugins. Redux is well documented. The Redux website has a knowledge base, codex (developer documentation), and video tutorials.
Bootstrap 3 WordPress
Roots is another WordPress Bootstrap theme, although it's designed as a minimally styled starter theme that includes Bootstrap, HTML5 Boilerplate, ARIA roles and Microformats. It also works with a number of preprocessors including LESS, LESS with pure CSS, SASS and Compass. Roots helps you build better WordPress sites faster.
Underscores comes with a multitude of neat features such as sample theme options panel, custom template tags, several pre-formatted layouts, custom header implementation, and useful add-ons called “tweaks” that can be activated easily through the functions.php file.