I don't have a Polar or looked through one. I do have a Magnus and it is outstanding glass, although I'm not a big fan of the illumination knob. The reticle would be a bit thin for low light without illumination. Their new Fortis scope moves the switch back to the traditional position on the left side of the scope.
Comparing the Magnus to my Premier, I would say the Leica is better in low light with more contrast, and the illumination goes way down low; and wins FOV at the same power. Color and depth of feild is very good in both.
Not a direct comparison, but in general if I could keep only one high end scope itd be the Magnus or buy a Fortis.