I've been working with Drupal for nearly five years now, and I've tried quite a few web-hosts on the way.  I run a web development shop specializing in Denver Drupal Development (Rehab Creative), and historically provided hosting for our clients.  A couple years back we decided to get out of the hosting game, and needed to find some reliable hosts to recommend to our clients.  This site is where we direct our own clients now.  I have first-hand experience with all the hosts reviewed here, and I've used them to host real Drupal sites (not just "test" Drupal installs, but actual functioning websites).