The leading open source LMS are moodle, sakai, Atutor, OLAT. There are dozens  of commercial  LMS, with few  that have dominant presence in the market like Blackboard, ANGEL learning, Desire2Learn.

We will use moodle as reference (Why?  Because we agree with UCLA, that as of the time of writing, this is the best platform to choose)

Moodle has excellent features for managing courses, learning and tests, but it lacks the clear and easy content management and publishing capabilities of Joomla, WordPress and SharePoint.

It also lacks integration with high quality conferencing suit. When we say "High quality" we mean something that really works, that you can schedule courses and classes and have confidence that they will be working without technical problems, low quality sound and video, and overload of support calls from users.

There are few third party conferencing integration to moodle, but each of them is inferior compared to the leading commercial conferencing platforms.