Flip PCB to the back side.
push/shove routing
obstacle avoid routing
easy creation and editing of diff pairs
To be fair to EAGLE, as of 8.5.0 and the inclusion of Push & Shove, which was released yesterday, over the last few releases Flip PCB view (8.4.0) and obstacle avoid routing (8.1.0?) are all now available, and EAGLE has done creating of diff pairs for a while. Granted editing isn't ideal, it could definitely use some more polish there. Also in 8.4.0, SPICE simulation was integrated into EAGLE with the inclusion of the ngspice engine. So, regardless of what people think of Autodesk, EAGLE is progressing faster than in has for an awful long time.
With regards to the SpaceMouse, I wish it had proper native support. I have managed to get it to work to a point in EAGLE (on macOS) but it's far from perfect.
If CS works for you and you are happy with it that's great. EAGLE isn't for everybody with the subscription licensing, but then CS isn't for everybody either. To be fair I have never used Altium products, I have used DxDesigner, OrCAD, and some older Mentor Graphics products too. Compared to all those, once I learned (and I mean really, properly, thoroughly learned) EAGLE I became far more productive than in any of those tools.
I suppose I should install CS in a VM and get a trial license so I can have more understanding of what it offers....
Best Regards,
Rachael