Leon Trotsky, Communist theorist and revolutionary who led the Red Army in the early days of the Soviet Union. After Lenin died, he came into conflict with Stalin, and ended up going into exile. He was killed by one of Stalin's assassins in like 1940ish with an icepick.
The biggest difference would have been avoiding the sino-soviet schism.
The modern hate within communities like hexbear and ml for Trotsky is kinda ironic given that most of them are fans of Mao. Especially considering the split between Stalin and Trotsky began over what to do with China.
Stalin wanted to support the KMT, further dividing the country and enabling him to take mongolia and parts of northern China. Trotsky wanted to aid the CCP, and eventually create a global network of communist countries. This ran counter to Stalin's agenda of communism under one united country.
Trotsky was inclined to empower the workers’ councils (Soviets) to be decision-makers. He was far more democratic than most of the other Bolsheviks. Not saying it would have worked, but I highly doubt it would have been worse than the Stalinist era.