Sounds like you want to build a web application and despite all the responses in support of WP it is not the best platform to achieve that job. WP vs. Drupal for a web application Drupal hands down. It is more difficult to learn but is more equipped to handle a web application. Expression Engine looks promising but for more advanced tasks would take custom programming where as, things like views, panels, features, fields, drush, web forms, etc could achieve with very little to no custom programming. I guess it all depends.
The power of Drupal doesn't lye in the core itself really. It lies in some very powerful contributed modules. Once you become familiar enough these key players the sky is really the limit. Though Drupal 7 has made some big stries in moving image cache and fields into the core. Maybe in a couple of years some other key players like panels and views will make it in. I know there is no immediate plans to do that with the release of 8 since the focus is on mobile, contexts, rest api and bridging Symfony components.
None the less, Drupal 6 alone is meh, 7 more useful but some very powerful contributed modules make the system hit that new level. I know of no other system that matches what Drupal can achieve with panels and views. Also, the WP concept of "post types" and "meta data fields" is pretty much taken directly from Drupal node types and cck (fields). It might not be entirely fair to say that because Drupal cck (fields) probably got the idea from some place else but Drupal did have those concepts in place before WP. If you can get over the system flaws it offers a lot.
Not to mention unlike WP no one is afraid to modify the core architecture to make the system better from an architectural stand-point. WP has had just about the same crappy code forever, with no change in sight. When really the entire thing needs to be gutted from a technical stand point because it is complete trash but designers don't care about things like that. They just care that stuff looks pretty and requires the least amount of technical knowledge possible. That is why the system is so popular, not because it is good all-around but is really designed for stupid people sacrificing architectural quality.