Mileena is nice too, but I like women with lips. Sheeva already has a nice body, and she has her own army. I'll get to smash the top shokan all day. Sheeva doesnt seem as violent as most say, she be my guardian shokan, and wife.
This hypothetical situation depends on several factors.
The main one is, does the character contain her genuine personality, or are we just talking looks here? Is the character in love with you? Because it must be said that Mileena is bona fide psychopathic, while Sheeva is at least reasonable.
Physically, I would enjoy them both. As far as Mileena goes, two words:
Lots of them.
This is Sarah: http://s323.photobucket.com/albums/nn474/Furious_Spanky/ She has big breasts, a big sword, big hair, and one eye. I'm in accounting.