Trotsky was wrong with Permament Revolution. Both Stalin and Sverdlov (had he survived) would have been good options, but had Trotsky taken power and actually implemented Permanent Revolution by attacking the peasantry inmediately, relying on revolution in the west with a larger proletarian base, would have resulted in the death of the socialist project. Trotsky hinged his entire theory on the inability for the peasantry to ally with the proletariat, when the opposite was found to be true Permanent Revolution ceased to have any relevance.

Trotsky's later behavior was that of a wrecker, consistently splitting from the party line, and that resulted in his expulsion. Trotskyist parties since Trotsky have maintained the same tradition, and split like cells undergoing mitosis over and over. This lack of party discipline and frequent splitting is core to the lack of success of Trotskyist orgs, and is also why the generally oppose AES countries.

Trotksy had some good moments. He played a pivotal role in the Russian Civil War, and wrote decent theory outside of the context of Permanent Revolution. However, both Sverdlov and Stalin were more capable revolutionaries with stronger understandings of theory and practice. With Sverdlov dead, Stalin was the logical choice, and that's why he was elected.