PrestaShop is your best bet. The only problem with PrestaShop is that uses smarty template engine and rather than write clean PHP without the need of loops etc, in smarty they have made it a very great deal of effort for the average person to theme.
I will stand behind PrestaShop 100 percent if they get rid of smarty and implement a simpler templating system such as a main html file with includes that you can just embed PHP template tags into.
