For me all the qualities my girlfriend has. Granted she's not perfect but to me her flaws make her better.
-She is a few inches shorter than me
-She has long brown hair
-She has an upbeat personality
-She is willing to look past my flaws (which there are a lot of)
-She has a lot of the same likes and dislikes as me
-She doesn't have the same opinion as me (allowing me to have a better view on another perspective)
-She accepts me for who I am and doesn't try and change me