Rouvy
I've been doing a 2 week free trial of Rouvy, been using Zwift for 4 years now. Rouvy's major claim to fame is you are cycling through videos of real world places vs. computer generated graphic representations.
It is very easy to use, the road feel is more realistic and the video view is a nice change and certainly more realistic. The down side of that is often (like in real life) you are riding through some pretty non-scenic stretches of roads! After car-free Zwift, it is pretty odd to have cars pass you, as well.
I like the user interface but part of the clean screen is because there is not texting of other riders - those messages on the screen in group rides are often very amusing or at least provide a nice distraction.
I did a beta test of a "spin" class on Rouvy, where we had to join a Google Meets group to hear/see the instructor and there was 9 of us cycling on the course. But, there was no "erg mode" so, the instructor saying "go to zone 4" might happen on a downhill with low resistance and "go back to Zone 2" at an uphill. There was no rubber banding, like in group workouts on Zwift, so the group split up pretty quickly.
In my other rides, I'm the only cyclist on the road - again, kinda realistic but that riding with others on Zwift also provides a distraction.
I think I'll stick with Zwift, but for those that don't like Zwift, definitely a viable alternative.