Considerations when choosing a theme for Drupal 7 + CiviCRM?
One consideration is to use different themes for the front office and the back office. 


The front office are the profile pages used to gather information from the constituents (or maybe you are using webforms in combination with webform_civicrm). These should be themed according to the official stylebook of your organization. They are part of the marketing strategy. It is often a limited set of screens, so almost any theme can be selected. But in these days responsive is a must, making bootstrap a good option.
The back office are standard CiviCRM screens used by your internal staff for searching and processing the data. These are complex screens, that work best with a simple, readable theme that uses the complete screen. I use adminimal for this task.


More of this discussion can be found at Theming Civi Vs Drupal.