Well you obviously look first so thats def. the first thing anybody is wanting in the opposite sex. (unless your gay, or your chatting with someone online/phone.) Then the personality traits come into play after you gaze at her/him.
Personality!!! There is a really HOT and I mean HOT girl in our class... but we can't get along whatsoever. If I answer a question and it is right... she will spend forever trying to prove otherwise. Also... the girl I like isn't "retty" is it called? So I looked at her personality and if I think about it.... we are almost the same so... yeah personality all the way.
52% of relationships are built upon personality, not looks (a.k.a. they are ugly)
Lol. How was it. Same programme where they times how long it took for someone to judge if they would want to date the person or not (3 seconds, woman being faster than men): Most people would go after a person in their league, which means that only the alpha would go for alphas. No regular woman would go after the hot model, because he would be most likely to leave for something better. And so on. PUPPIES OR KITTENS!
Both. Kittens are more of an insta-dose of cuteness, while pups are more hug-ish and aww.
But in response to OP: "Judging" by behaviour and looks first. Then the rest of their behaviour and personality. I've never started to like someone because of their appearance (though I do notice appearances), but getting to know someone's personality takes time, time you probably won't spend unless you like them.
You need a mix. Personality is everything. But if the person is REALLY ugly, then you won't like he/she. And you could know a very pretty person, but with time, his/her personality will determine if you can be together or not.