Arwen. It's a more romantic story, you know? Elf-mortal...gives more drama and tragedy.
Don't get me wrong, Eowyn's an excellent character, but she and Aragorn are just wrong for eachother.
I like the graceful, elegance of Arwen. When she's next to the rugged, manly Aragorn, it's like you can see his weakness...it's beautiful.