Among the on-line courses I've taken Thinkspace is one of the best! The others in that narrow category would be Scoreclub and Art of the Score
Scoreclub - Alain is an outstanding teacher, not quite as fun as Guy, but that's ok. I am a little disappointed that he went with a subscription model, his courses take quite a bit of time and effort to get the most out of them, and I can't always dedicate that much time.
The Art of the Score - this is more of an analysis of "famous" scores. It's a fun listen, and I get something out of most of the podcasts.
Don't overlook Groove3 - there are lessons there on nearly every topic, and most any level.
Mike Verta Masterclasses - if you can dedicate 3 or 4 hours, and don't zone out when he wanders off topic then you can get something out of them. These were some of the first online classes I took, and I don't regret it, but I haven't been back there in years.
And there are others, Musicnotes Now has some gems, and there is someone that I can't think of now that uses a text to voice "thingy" named Nico as his assistant. If I can remember the name I will edit this post to add it.