I have licenses for 7, 9+10, and haven't touched any since 10.3.6... While I did nab a PT First license to check out what they're doing in 12, I played around with it for maybe 10 minutes without really trying to find anything that made me want to use it for production work.
Back in 2013 / 2014 I worked on a short film destined for festivals that wanted full surround treatment (which was also my first experimental attempt at production sound and audio post for more than just stereo/2.1 video production) and Sonar Producer X2 at the time just caused major headaches when trying to work with surround. I launched a "motion picture workflows" thread around the time I was working on the project and tried to document my experience, and share my bottlenecks and workarounds / solutions. I haven't touched Surround since then because it was just a nightmare and I'm not set up for it commercially though I've actually had a major indie feature try to get me to do audio post in 5.1 theatrical treatment! (yikes)
I will hand it to Avid for catering to the top 1%. Right now Atmos is the primary platform for most Studio tent-pole films and Atmos is exclusively configured to integrate with Pro Tools, though I've heard a couple of engineers supposedly playing with it in either Nuendo or Cubase (though i'm pretty sure it wasn't Cubase).
The VR segment certainly has been getting some help with ambisonic plugin formats within PT, and Nuendo has this cool middleware integration which really helps their game developer segment with quickly iterating sound FX and audio to get it into the game engine and playable.
While Sonar still has Surround Bridge and surround busses, I really wished they would have solidified surround processing better. Maybe that's changed since X3 and the introduction of VST3 spec, since there are quite a few benefits to allow channel/parameter determination on instantiation rather than having set stereo, multi-channel, and/or mono plugin versions in VST2.x format, but I just haven't even tried since that project turned me off to it so harshly.
If Sonar has improved the Surround workflows in Platinum I may have to give it another shot as soon as I can make the time to dig up something to experiment with.
I still just don't care for PT workflows. I laughed when they announced offline bounce!