Under option 1 the axis would win
Stalin may have been crazy, but he wasn't stupid. There was no way he would risk signing a seperate peace with Hitler. and the Germans would not have been able to mount a successful 1943 offensive. The German 6th Army, while not destroyed, would still be pinned down and unable to effectively maneuver thanks to Hitler's obsession with Stalingrad. Basically this gives the Allies time to launch a 1945 Balkans invasion that keeps the Soviets from controlling Albania and Bulgaria. Also the Czech Republic and Austria get to escape the Soviets. We also have a chance to avoid a DPRK. That's all to the good. To the bad, we've probably seen at least five A-bombs used in Germany and US war dead are at least a quarter million higher than OTL. (Berlin, Nuremburg, Hamburg, Munich, and Vienna make a good list of A-Bomb targets.)
I don't know, my theory was much simpler. Firstly, the USSR was on the verge of collapse at the end of 1941, using troops from the eastern theater to replace those lost in the west, including for the December 7 counterattack near Moscow. Secondly, the "America First" movement was much stronger in the U.S. than during World War I, with most Americans firmly against direct participation in the war. The collapse of the USSR would not have changed that. Caught between the Axis powers, and achieving only minimal aid from the British, the USSR would eventually have lost the war. Not necessarily surrendered, but just defeated.
