What may forever be debated and never resolved is the issue of how many German divisions were either pre-occupied or, ultimately, destroyed on the different fronts. The Russians kept millions of German soldiers on the Eastern front and killed or captured huge numbers of them, which, in turn, meant that the Western Allies did not have to contend with them in their theaters of operation. The reverse is also true, though on a somewhat lesser scale: the Anglo/American West kept large numbers of German forces from being available on the Eastern front and/or forced the Germans to draw on forces that were fighting elsewhere.
The calculus of just who created the greatest strategic benefit is almost impossible to reckon, but, without question, the Russians, regardless of their kill ratios, tied up and destroyed huge numbers of Germans, which I believe was their greatest contribution to the Allied victory.
True. But also don’t forget the Germans tied up an astounding amount of resources trying to kill Jews-—guards, trains, etc. At critical times when the Germans needed transportation to the east, the trains were still moving Jews.