The USSR would span its territories in the 80s but be led by a competent Marxist leninist party. Same for the Warsaw pact countries and Yugoslavia. These were caused by revolutions popping up all across the globe and other areas.
The US choice would have itself devolve into chaos while its power and influence decreases. Infighting would break the US into pieces but territories like hawaii and alaska would gain independence. The main government would be torn asunder and the CIA rogue and unfunded.
I definitely choose the revival of the USSR and cooperation of the recreated governments of Warsaw-aligned, Yugoslavian, Balkan and former Latin-American and asian socialist countries united.
Wishing the U.S. would desolve into chaos and destruction is foolish, and an entire rube goldberg worth’s device of ways that could go wrong and backfire or make the global situation worse.
This power vacuum would turn into a smoldering crater of fascism, capitalist oppression and a wounded gazelle gambit willing to render large swathes of the Earth uninhabitable just to spite humanity out of socialism.
Where as a united principled and effective communist and anti-imperialist bloc of countries would eventually lead to the downfall of capitalism.
Damn, that would be a gigantic global movement, it would essentially push most anti-imperialist countries to a crossroads of capitalism or socialism rather than a state capitalist anti-imperialism. Like Nicaragua and Venezuela and Palestine could become Marxists in that case that would be so much more based than the fall of the current global leader. Whoever Western Europe supports after the USA falls will continue the military, but a giant global alliance against capitalism would fight against that