When a school wants to offer courses/degrees online, they usually need a method of delivering the course content. That's where learning management software comes in, application suites that deliver the tools needed for professors to reach their students. This allows for the creation discussion forums, tools to build quizzes/tests, etc.

The dominant players in this market seem to be Blackboard and Desire2Learn. I've used both in the past, and while both were usable, I really preferred Blackboard. While I didn't like their website interface, they offered a rich client that you could download to your own desktop which made things MUCH easier to use.

Which one(s) have you used?

What did you like about it? Dislike? 

Have you found any one that's better than Desire2Learn or Blackboard?