I definitely get turned off by "young" teens. Some girls look like they are 14-16. I also don't like the "teeny schoolgirl" look with the obnoxious tights, the ponytails etc. Gross actually.
18-45 I would say. Age doesn't matter to me as much as body type. The girl can't be rail thin with no curves, then she just seems too immature. I want a girl with a lot of curves.
When I was in high school I found myself hitting on sophomores and juniors when I was a senior. As I started to become older I realized that older women had this confidence I never saw in women around my age and younger than me. Still to this day I find myself hitting on older women. Older women I think know what they want and are to the point when it comes to anything and everything.