I am glad we can agree on that.You post, "I don't think the efficiency or 'success rate' are suitable measure of morality or badness and goodness in this respect." Neither do I.
Hitler's regime's intent against the Jews was, from 1942, more implacable than anything Stalin unleashed. Hitler's regime was intent on killing every single Jew within reach, of whatever age, including new born infants, as a matter of policy. There was no escape for them because the Nazis themselves defined what they meant by "Jew". Jews could not recant, or be re-educated, or complete a prison term for the "crime" of being Jewish under the Nazis.
However, I think this argument too is problematic because you can substitute the words 'enemy of the people' into the equations you give and 'Soviets' for 'Nazis' and the statement would, in my view, still hold. Once accused of being a Jew by the Nazi state, you could try to prove you were not. Good luck with that. The same is true of someone accused of being an 'enemy of the people' in the Soviet Union. Perhaps the only difference is that there were more definitions of 'enemy of the people', than there were of 'Jews' and that priority shifted from one sub-group to another more in the Soviet Union. In short the same activity was being carried out, just on a wider front. I can't see how the fact that that Stalin appears to have been more mercurial in who was to be murdered on a given day, makes him any better than Hitler. Would we be saying that Ted Bundy was a worse serial killer than Andrei Chikatilo because the former murdered young girls and women while the latter was less discerning in his victim selection?
From the point of view of the 'statistical' citizen, one could argue that life under Hitler was less worrisome. Unless you happened to be a member of one of the unfortunate minorities that Hitler disliked - Jews, Gypsies, Communists etc, so long as you minded your ps and qs and took care not to antagonise the local party informer, you could be relatively secure. In the Soviet Union, you had the constant worry that for some reason, often absurd and usually entirely out of your control, you could become a member of the 'enemies of the people' overnight.
Also, I think, the data is skewed when we only consider people who were murdered directly by bullet, gas etc. The White and Red Czar's Empire had a resource that AH did not - the ability to move whole peoples thousands of miles and to dump them in appalling conditions exposing them to crippling mortality and morbidity. This was a tool of genocide, in many ways as effective as mass murder - with the Circassian Genocide of the 1860s proving just how effective it could be.
However, I would point out again that the comparison of the fate of the Jews with that of the Ukrainians is yours not mine. A comparison with the fate of the Crimean Tartars and many other peoples is probably more apt. Or of the Polish, German and other 'national' operations of the 1930s. Clearly the intent was to destroy anyone who belonged to those ethnic groups.
This is not directed at you, Sid, but I can't help the feeling that the argument Stalin's apologists are intent on making is that 'I didn't drown him m'lud. I merely chucked him overboard knowing full well he couldn't swim". I don't buy it.