I took the Ecotech online PV Advanced Training course for the NABCEP program. At first I was skeptical, as you are paying for a service that you do not get to 'try out' necessarily. However, the service is great. The slides are easy to follow, and the information is not too dense. It's broken up into a lot of sections, so do be prepared to spend some time on your courses. I spent about 8-10 hours a week and it took me just less than 2 months.
The main thing that stuck out to me about my experience is the quick response and care that the support team shows for their students. After emailing them a questions I got an answer within 12 hours, and they were extremely helpful.