I'm not sure Stalin and Beria were much different to psychopathic, oppressive, out-of-control tsars or nobles. It's not like you have to look that hard for equivalents in tsarist times who committed atrocities - just they generally had less technologically advanced tools and systems.What strikes me is the difference in how they dealt with dissidents. I'm sure the Tsars were not all puppies and rainbows(Lenin's brother was executed for instance) but exile to Siberia seems to have been a common punishment. Not fun at all, but remarkably lenient compared to the Soviets torturing people to death in Gulags, or whatever Beria was up to.
The USSR was potentially better for non-Russians. After all, the Russian Empire was an imperial project for the benefit of Russians, who exploited the areas they conquered whether Ukraine, Caucasus or Siberia as brutally as any empire did its subjects. The USSR at least viewed non-Russians as full and equal citizens in a joint project.