My recommendation is to actually create your own. I work in a store that has about 20-30 user themes per year, all of which have real similar functionality, but are usually not standard / common in most topics.
Then, whenever you need to develop a new theme, we basically copy / paste this set of default template files into a new theme folder for installing WordPress. For us, the elements that we turned on by default are pre-populated header.php, footer.php, index.php, home.php, single.php, functions.php, comments.php, / images (dir ), / functions (dir), style.css, / css (dir), / scripts (dir) and several other elements.
Then we also used the framework of Yahoo Grids, 960 or Google Blueprint to speed up css. There are several other items / files that I leave but should give you a general idea of what works best for us in our store.