It's now widely accepted on the left, including by myself, that the Left Opposition led by Trotsky - or, for that matter, the Right Opposition led by Bukharin - would have mitigated the worst features of the Stalin regime, particularly in regards to the accession of the bureaucratic machine, the destruction of the old Bolshevik party, and the paranoid lies, odious cult of personality, and savage police terror which weighed on the Soviet state. But apart from conducting itself more in accordance with democratic socialist norms inside the USSR and within the Comintern, is it realistic to expect that the Opposition could have industrialized the country and secured the allegiance of the peasantry at a more measured pace without being forced to make similar foreign policy concessions to keep the allied powers at bay? Neither Bukharin nor Trotsky admitted of that possibility. Trotsky, in fact, did not think the the Soviet Union could survive in any form unless the revolution spread to the advanced capitalist countries, and that the first priority of the Soviet leadership therefore was to do everything in its power to foster this development.
^^^^^^ CB: In my opinion, an error of "20/20 hindsight" in evaluating history is critical in your analysis above. Now we know there was no attack on the SU until 1941. But at the time of the decision on crash industrializing it was not certain at all that an imperialist invasion would not come sooner, even right away. In 1918 , Britain, France and the US sent troops to strangle the revolution in its crib. That was the recent empirical experience the Soviets had with imperialism's actions toward the SU. The threat of invasion was not just from Germany. Stalin and CPSU were very non-delusional and realistic in pushing crash industrialization, as the only way to survive the invasion that they knew was coming was to build their industrial base for an industrial strength defense. Without it , the Nazis probably would have won.
I disagree that the Soviet Union could do anything much to foster revolutions in other countries, a la Trotsky, because the Communists in those countries would be defeated on the basis of nationalism and interference in other their country by a foreign power. Stalin's or Trotsky's fomenting revolution in other countries would have been a kiss of death for the Communists in those countries. That happened anyway, but Stalin and them were conscious that Soviet agitation in other countries would have made it certain to happen. Also, to the extent we are comparing Leninism and Stalinism , it was Lenin who formulated the idea "peaceful co-existence and competition of countries with different social systems". So, in this regard , Stalin and the CPSU were Leninists.
The claim that the Soviet Union had nothing significantly socialist in its history is false.