Seriously this is more difficult to really decide. In the film I'd have to say Arwen. In reality, while this might buck conventional or even popular thought, I think Liv Tyler looks mildly retarded and is amazingly overrated. I've always found it difficult to find more than just cute and almost never attractive to the point of trying to split her in half.
So I'm thinking its more of a question of Miranda Otto vs. Cate Blanchett vs. Liv Tyler....
VS
VS
Good conscience says that I can't vote on film appearance alone and looking at the three outside of costuming I have to give my vote to Cate, who is shockly more attractive than she is given credit for via roles or in the mainstream press....