Finding unbiased numbers is hard, obviously. Maybe we'll know more about it 50 years from now, but at the moment our knowledge is approximately what it was for the Soviet Union right after Stalin's death or so, yes?

That said, I have yet to see anything resembling a credible source that claimed more than 10,000 direct deaths caused by the Castro regime. I've seen much higher numbers (50,000 or more) in terms of indirect deaths: people trying to get out of Cuba and drowning in the process.

The population of Cuba around the time of the revolution was about 7 million; now it's around 11 million. The population of the Soviet Union in the 1930s was between 150 and 200 million (good statistics are hard to come by; see https://en.wikipedia.org/wiki/Soviet_Census_(1937) for why). Even if we take the extreme 7 million and 200 million numbers, 10,000 Cuban deaths is equivalent to about 285,000 Soviet deaths on a per-capita basis. And that's over a 50-year or so period. So yes, Stalin killed a lot more people no matter how you count it. Of course, "leader who killed a smaller percentage of the population than Stalin" is a _really_ low bar; pretty much everyone except Pol Pot clears it.

In general, the "Cuba under Castro" numbers for political violence don't seem any worse than other Latin American countries in the 20th century. Again, this isn't _good_, just like it's not good that we can end up talking about "oh, that's equivalent to hundreds of thousands of deaths on a per-capita basis, which is _tiny_". :(