This is the question that is at the heart of this book. It is important to remember that one way of viewing this book is that it is a critique of humanity and in particular of our evil and uncaring nature. Let us remember that it is Frankenstein that rejects his creature after creating him, when he was in most need of care and love. Indeed, the creature himself, in Chapter Ten when he confronts his maker after killing William, indicates that his inhumanity is in no small part thanks to the inhumanity of Victor himself and the human race:
Believe me, Frankenstein: I was benevolent; my soul glowed with love and humanity: but am I not alone, miserably alone? You, my creator, abhor me; what hope can I gather from your fellow-cretaures, who owe me nothing? They spurn and hate me. The desert mountains and dreary glaciers are my refuge... If the multitude of mankind knew of my existence, they would do as you do, and arm themselves for my destruction. Shall I not then hate them who abhor me?
There is a chilling logic in the creature's arguments. Why should he not respond in kind to the way that he has been treated by both his maker, who should have cared for him and looked after him, and by mankind as a whole? If the creature is inhuman, it is only because he is imitating the inhumanity of the human species. Therefore, I think that the novel presents Victor as being more inhuman.
I think the creature is more human. This is because the creature expresses his feelings more confidently and to a greater extent. Also, the creation wants to be involved in society, seemingly more so than Victor.
Victor is alien in his society in the way that he removes himself from others, for example when he goes about creating the daemon/creation. Victor is very secretive and seems to like it that way... he doesn't really try to understand people like the creation does.
The creation tries again and again to belong in the community, its his greatest desire. With Victor, on the other hand, there seems to be a gulf between him and the rest of society.