MOOClab (https://www.mooclab.club/threads/best-mooc-providers-and-their-pros-and-cons.572/) do an analysis of the strengths and weaknesses of the following MOOC platforms:
- Khan Academy
As always it depends on what you want from the course. Consider the following points:
- For the widest range of subjects try Coursera, eDx or Alison
- For science and technology subjects explore eDx first
- Open2Study has a great user interface but is focused on the Australian market
- Alison has a very wide range of courses but an annoying user interface that forces you to watch advertising.
- Khan is a really good provider with a vast range of courses but does not offer certification.