If you're talking about immediate physical attraction I would say the eyes...eyes always get me and no matter what you look like if you're funny and you make me laugh I'm attracted to you right away. (That's what got me about Joseph)
However personality like I said funny, but knows when to be serious. Smart, but not afraid to say "I don't know". Protective, but not rediculously jealous. Sensitive, but still masculine(sp?).
Most importantly he has to like me for me..not for what he thinks I can give him or what I look like. Honestly I love being made to feel like I'm important to him..the little calls just to say I love you and the time he takes out of his day to do things for me mean a lot to me.
"An it harm none, do what ye will."