OK. since you want to know and almost everyone is saying all the nice things. I'll list them
1. Hair (most guys (and all guys I know) like girls with long hair(shoulder to boob length)
Wavy Hair, or Straight Hair. Short hair is generally deemed unattractive. I personally don't like curly hair, but some guys do.
2. Face (Large eyes, Full lips, small cute sharp noses, clear skin, nice thin eyebrows that bend in a curve) An ugly face would have Freckles, acne, small eyes, angry large or bushy eyebrows, large noses, thin purse lips.
3. Body- Fairly self explanatory ( B-C or D cup breasts), some guys like large butts, others like smaller but firmer. long shapely legs, curves. Not a lot of body fat. An ugly body would generally look like a pre-pubescent one, A- cup breasts, flat butt, little or no curves.
4. Height- Depends on the height of a guy, most guys like girls 5 inches or more shorter than them. But ya anything above 5 feet and anything below 5 foot 9 is generally considered attractive by most guys. Girls over 6 feet tend to have a hard time finding suitable guys. Girls less than 5 feet can always wear high heels and find a shorter guy. I think the majority of women fall in between the 5-5'9 category
5. Personality- you didn't ask for this, but if we want to get to know someone and know if they are girlfriend material and possibly even future wife personality will play a much larger role. A 1 night stand personality wouldn't matter much, but if the guy is interested in settling down personality could play as much as 90% in their desicion. A mean personality like, focusing on oneself too much, being a gold- digger, high matinence, but this REALLY depends on the guy.
In general looks will attract first, but personality rules in the end.
I have described a model if not a supermodel here, so obviously no normal woman would match all those descriptions. But those are the obvious attractive qualities of women