Drupal theming can be much faster and easier when you use base (starter, parent) theme as a foundation. A base theme usually has nearly no css styling, provides theme regions, advanced features, and its purpose is to enable you to create new themes fast, focusing on changing design to code.
Base Theme Classics
Zen is the ultimate starting theme for Drupal. If you are building your own standards-compliant theme, you will find it much easier to start with Zen than to start with Garland or Bluemarine. This theme has fantastic online documentation and tons of code comments for both the PHP (template.php) and HTML (page.tpl.php, node.tpl.php).
Framework is a blank canvas for theme developers. Use Framework as a user friendly starting point to help facilitate your theme development.