well Sephiroths mind was taken over his body was that of a warrior among warriors so would Jenova choose Sephiroth or Cloud since them two have the most jenova cells i think but Cloud was schizo at the moment and Sephiroth's only weakness was mortality and being human
Wait...so jenova "possessed" Sephiroth? I still don't get how you can be fighting the 'real' Sephiroth when he's supposed to be stuck in the mako. I don't get it.