If you're after the sense of space, Dolby Atmos on Apple Music falls flat on its face. The expansion of the sound stage is marginal at best, if there is one at all. When I heard about Dolby Atmos and Spatial Audio for Apple Music, what I imagined was binaural recordings, but done using DSP. To be frank, I didn't even get that. Or maybe they were trying to go for that and do have quite a bit of room for improvement (IMO).
The only saving grace for it is that to my ears, it's a lot less "stuffy;" there is a lot less congestion that happens and it adds a ton of dynamics to the music. By that same token, not everything is the same volume, the balance between instruments differs; some of my friends hate this portion of it while I absolutely love it. Gives the music a lot of interplay and the mixer some freedom to kind of give it their twist that they want on it. The result tends to create something that sort of sounds like it's trying to be live though, but those do a much better job conveying space.
So during all my testing I preferred to listen to Atmos out of my more neutral headphones (Euclid, Etymotic, Mobius, etc.). They're all closed back and with the exception of the Euclid, none really do well with sound stage in general; they tend to give you something a bit more intimate or portray what's there. I will admit that with those set ups, most of the recordings sound a lot more natural to my ears. I did eventually go around to plopping on a pair of open-backed headphones, my HiFiMan Ananda BT. I never really noticed a sound stage with the headphone, it was always excellent with separation, but I never noticed a sound stage. Well, I did notice it with the Atmos recordings. While the Mobius was able to create a sense of space with it's head tracking by placing the sound in front of me, it was still quite intimate and small. The Ananda seemed to give a wider presentation than I'm used to. That said, I still don't get the sense of true distance, just bigger. I don't get the sense of a room or even other there or in that direction, even with the Ananda.
One thing I will note, since it's been mentioned constantly, vocals are pushed back. The only fix for this is to have a linear setup, many would call it analytical or mid-focused. So a V-shaped headphone will definitely end up worsening this aspect to the music.
