What are the best cloud-based Learning Management Systems?

Course Authoring
Course Builder
Course Delivery
Learning Paths24/7 Availability
Content Sharing
Video StreamingSession RecordingFile Sharing
Collaboration
WhiteboardHand RaisingParticipation ControlsSurvey ToolsScreen Sharing
Functionality
Technical SupportLive ChatMarkup Tools
Training & eLearning
Content Delivery and Tracking