A while ago we chose to focus on open source web solutions. Our open source framework of choice is Drupal. Here is the reasoning behind that decision:
Massive developer community
There is an army of developers contributing to constantly better the solutions in place and solve any issues which may arise. Drupal.org has over one million registered members. Any issues get spotted very quickly and resolved efficiently and effectively. All members of the community benefit from the collective knowledge of so many skilled Drupal experts.