Are you planning to do do anything other than Wordpress ?

if yes, then may I suggest Drupal. Drupal 7 is already gearing up to be an amazing framework and it is a seriously untapped market. I have lost count of the number of times people have asked on IRC about a Thesis like theme framework for Drupal (Acquia is not quite it).

Another popular request is an admin theme for Drupal that is geared towards people used to Wordpress (me included).