Classic Juggernaut in both. Serpent Jugz hasn't done anything worth mentioning yet. So I'm going with classic Juggernaut because at least he has a few decades of feats to draw upon.
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..even the outer hells are indifferent matters for they bow only to potent and archaic Nodens.
satanna said jugs could have resisted posession but chose not to. the thing is that cytorrak wants cain to become a mindless destrcution force willingly and isnt proactive about it at all. he doesnt really care about giving him more power, taking it all away to find another or even forcing him into the path.
Cyttorak just wants his name to be known, not destruction per se, else Doctor Strange wouldn't be one of his most frequent 'clients'.
The way I see it, Cyttorak figures Cain can spread his name better through destruction than through acts of benevolence as it fits Cain's nature better to be destructive.
As it is, he's not spreading Cyttorak's name, he's spreading the Serpent's.