Personally, I'd like to think Kirak would be superior. He easily overpowered Vader's initial Force choke, and he seemed to be Vader's superior during their final clash.
*But I'll also note that this was a n00b Vader(literally a few days off the operating table), and his armor was heavily compromised at the end.
It's from Marvel's official solicit for issue #3. Could very well be canon.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."