So base Enma=Black Shuusui?
Considering Enma still will become black, than Enma is better.
If base Enma>Black Shuusui, Enma is also better.
If base Enma<Black Shuusui, he took something inferior to fight Kaido.
If black Enma=Black Shuusui, again, he took something inferior, because there's the haki sucking gimmick.
And if Zoro masters Enma's gimmick, what does it say about Oden, who used two Enmas? (as far as we know, ame-no-habakiri might as well be just as gimmicky).
I just consider base Enma>Black Shuusui because it makes it less moronic to think about. But, in the end, is more something to wank Oden, than it is to wank Zoro.
Trash ass magic blade.