My two cents on 1917 and some on the state of the U.S. today.
I'm inclined towards Leon Trotsky. I'll give a cliff notes version, however I have not read the material in some time so there may be some inaccuracies. I encourage you to do your own reading. Marx didn't foresee imperialism which is basically the transition from colonialism to imperialism. Imperialism is the export of capital (ie. factories vs goods) and the domination of finance capitalism. The export of capital to Russia created a working class. Since capitalism was in decline, Russia from Trotsky was an example of combined and uneven development. It had industry, but a backwards peasant class was the majority of the population. In these cases, the working class had to make a revolution to complete the tasks of the bourgeois revolution by giving land to the peasants and seize industry and large merchants to have a planned economy. Russia, unlike the imperialist powers, was hard pressed to carry on the war. The Bolsheviks with the peasant Social Revolutionaries seized power based on soviets of workers, soldiers, and peasants based on the slogans of peace, land (for the peasants), and bread (which was hoarded by capitalists to gouge prices). These extreme war circumstances didn't happen in the imperialist countries although Germany came close with a revolutionary crisis in 1918 without the same circumstances.

In Trotsky's "The Revolution Betrayed", Trotsky explains what happened in the Soviet Union. Lacking the educated people to replace the Tsarist bureaucracy, the Communist Party had to rely on them and try to control them so that they served the revolution. Lenin once said that these guys outnumber us. It's hard to tell if we are running them or they are running us. Temporary measures were taken during the civil war and invasion of imperialist powers to protect the revolution such as banning factions, etc. (this is my interpretation) The bureaucracy didn't want the realization of a workers state where their jobs would be subject to election down the line or being controlled in general. In general, Stalin became the voice of this bureaucracy and used his power to kill or disappear all but himself members of the Central Commission. Trotsky, who had influence over the Red Army, was against a coup against Stalin as that would have created a different problem. Stalin eventually killed the entire Civil War officer core shortly befor Hitler invaded Russia. So, the revolution was not about Stalin’s policies as after he died, there was never a time when everyone but one person was killed because Khrushchev,etc were non-revolutionary bureaucracy, but still a deformed workers state (property was nationalized but there was no real rights to vote).

The crises in imperialist countries are different. The U.S. having the worst revolutions in that the first one maintained slavery, so it didn't even give democratic rights to all. Then, the Civil War, the 2nd revolution which firmly established capitalism was followed by a reaction after the withdrawal of Northern troops into Jim Crow. The legacy of slavery means there is no labor party run and composed solely of the Trade Union bureaucracy and workers. Black and white workers don't see themselves as workers enough as most whites are racist, don’t understand how racist the country is, or won't follow black leadership. There will be no U.S. revolution until there is a real labor party, not a bunch of millionaire suits funded by the corporations getting thousands of dollars in speaker fees. There could be no revolution as long as Jim Crow existed and the majority white workers were either for it or not lifting a finger to protest it.

Trotsky said that there are 3 conditions for a revolution: the ruling class has to be divided, society can't go on as it is, and of course a revolutionary working class party to lead. The division of the ruling class has to significant like in Russia one side with Kornilov trying for a coup vs the democratic bourgeois. The war created an intolerable situation with casualties and high food prices, etc.

One common misconception is that the Soviet Union was a communist country. They called it a communist revolution because it would lead to communism with need for a new revolution. First there is a workers state where major industry and retail is owned by the state and planned. This is what the USSR, China, North Korea, actually are/were: workers states without the necessary elections to prevent corruption. Then, comes socialism which is each according to his needs and ability. Then, communism has no state since it has automation of practically everything and people only working if they needed, but they are benefiting from the automaton in that they get goods and services as if they were working. In order for people like Stalin and Mao, etc to fool people they say that Marxism needed to be "updated" to reflect changes in the times. In actually, these updates took away the necessary parts and gave it a bad name. Trotsky made the actual necessary changes.

There can be no revolution in the U.S. without majority black leadership as black workers have the least illusions in the government due to systematic racism that permeates society. A slave owner (Washington) is STILL considered a “hero” in this country. It has NOT fully denounced slavery as Confederate statues show. Black workers will have to get rid of their backwards social attitudes (those who have them). All workers have to support state ownership of major industry and retail, resources, with state planning. It must have immigrant leadership and defend immigrants as well as LGBTQ, women’s leadership, etc. I’m sure that I’m missing something.