Of course it differs a great deal from one man to another. I often have friends point out a woman and comment on her beauty and I keep looking for the beautiful one. That goes both ways as well.
It has also changed throughout history. There was a time when fat women were all the rage and there was a time when flat chests were the in thing.
Now to me personally. From a distance I tend to like tall women; even though I am not that tall (5'8"). It is fine if she is taller than me.
I like a woman who is slender but not skinny, a bit of tummy doesn't bother me. I like women with large breasts so long as they came that way from the factory. Breast enhancement is OK if it is within reason. Very large is OK if it is OEM. I like a woman who carries herself with confidence. B / C, D+, A...it is really more about proportion.
Up close; The first thing I look at is the eyes. I don't have any set criteria. All shapes and sizes can be beautiful but they should be sparkley and lit up from within, my favorite eye color is green, followed by grey and black is at the bottom of the list. But If the eyes are expressive color doesn't play into it much.
Next is hair; I love long hair, like a bit of curl and very curley doesn't bother me at all. I prefer fine silky hair no matter the style, length or anything else. I like hair colors in the order of Red / chestnut / auburn, Black, dark brown, light blond, dark blond, other. I almost always prefer the natural color over any dyed hair. Different ethnic hair is fine.
Skin tone makes no difference to me at all and neither does race.
Broad shoulders are preferred as is a small waist. I tend to like "Hippie" women with a well rounded butt and I will take a slightly bigger butt over a flat butt every day.
So now you know why I am single ;-)