I have a site in mind that needs a cart for a handful of products and a blog. It also needs a custom comparison page where a visitor could select one or more choices from check-boxes relating to the product functionality they want and then the site returning the most suitable choice. It also needs automated emails to be sent to customers in the weeks and months following their order.... to request reviews for example.

drupal + ubercart?
WP + .....?
opencart + .....?