Who has used either or both of these options? One of my biggest goals is to be able to solely use my Mac, so either will work. What differences have you seen in the toolpathing between the two? Is one more efficient than the other? Any other significant differences in workflow or end results? Thanks!
I just started evaluating Spark. Hope to have a video out shortly on my thoughts.
If you know Vectric on Windows, Spark should be an easy path for you. If you don’t, well, wait for the video 
No experience with Millmage.
I use Easel and Fusion. Used to use Carbide Create but they removed the ability to export gcode without paying - hard pass for me.
-Tom