Is the pilottraining.ca online ground school accepted by TC? How is the course?

An "approved" ground school is one that is conducted by an FTU. pilottraining.ca is done by Harv's Air which is an FTU, so yes, it's approved.

It's approved, widely used, and I have yet to come across a flight school that had a problem with students doing their ground online. I did my PPL and currently CPL with it and found it to work well. There are hundreds of hours of available material, both in the form of Powerpoint presentations and videos. The videos are fairly dry, but very informative. For some topics the Powerpoint slides are sufficient, while for others you'll learn more by watching the videos, which are almost excessively thorough for the PPL exam. The practice quizzes and exams will make sure you're prepared for the TC exam. For what it's worth, I scored an 86% on my PPL ground.

As someone who works a weird full-time schedule I like that I can do the courses at my leisure from anywhere in the world. The cost is likely also far cheaper than what you'd pay to attend an in-class course. On the other hand, you lose out on the group participation aspect - pilottraining's online forum isn't really engaging - but I don't see that as a huge loss.

I haven't experienced pilottraining's competition, but I think they delivered on what they promised. I'm a satisfied customer.