FWIW: the platforms I've tried so far, in order:
FulGaz: app tends to crash, didn't get to try it much because of hardware issues.
Rouvy: data is good, video freezes about 1 hour and 5 minutes into the ride. I like the workouts, but it sucks to spend the last 25 minutes of a 1.5 hour z2 workout looking at one spot on a random gravel road in New Zealand.
Zwift: very heavy app, loaded once on my phone, wouldn't load again.
BKool: video works, data is wonky. It gets power data from the trainer, no cadence sensor, but it insists on guessing cadence. Trainer resistance adjustment is unreliable, too: some routes seem better than others, sometimes no discernible difference in resistance between 3-4% and 10-11%. I kinda wish it either entirely didn't work or had a shorter trial period than 30 days.
BKool video with everything else about Rouvy would be great.