Please make the argument.
On one level it is a hard comparison to make since Hitler was stopped. What would the world have looked like had he not? That is speculation. But is it hard to believe that the killing machine that was Nazi Germany would not have outdone Stalin? In a time versus killing ratio Hitler was supreme.
True ... and Stalin was not, to our everlasting shame.
In a time versus killing ratio Hitler was supreme.
I think there's more than just correlation, there. Hitler knew his time was running out, and cranked up the pace accordingly. And Hitler was more into industrialised (for lack of a better word) mass murder; Stalin was into mass starvation. That takes longer ... but he had time on his side. As to what the world would look like if we hadn't allied ourselves with Satan (Stalin) ... there's no way that two evil megalomaniacs like Hitler and Stalin would have been 'good neighbors' for any length of time.
"In a time versus killing ratio Hitler was supreme"
What numbers are you using for Stalin's total kills in the USSR during the purges? I have seen numbers as high as 10 million or more, though I suppose the truth is not known.