Late 20's-early 30s with race taken into account if she takes care of herself. Usually past 35 its just a matter of slowing down the aging as much as possible in which women try to keep themselves from looking old until they hit about 50 to where aging usually is inevitable. Luckily for dudes we actually peak much later and can usually eat off of this crowd in our early 40s if we take care of ourselves. If you have your Jon Hamm/Shemar Moore swag on, this age range is easy pickings.
Black women age much better than white women and usually blonde white women age the worst out of everybody. During that late 20s and early 30s peak, women are at their prime sexually, if they exercise regularly, their bodies are on point and mentally their head game is at a much more level space which makes them look better and less prone to the BS ass mind games early 20 year old chicks like to play. That whole combo makes that late 20s-early 30s age range the sweet spot for women with their shyt together.
Carrie Brownstein from Portlandia is going to be 40 in like a week and a half and she still looks like she's in her early 30s. She's jewish so I don't know if that has anything to do with it.
Lindsay Lohan is only 28 and looks

already from the drugs, partying, cocaine, etc.
Yvonne Strahovski is 32
Krysten Ritter is 32
That late 20s- early 30s prime is

. Old enough to have an interesting and mature personality with the right amount of life experiences while still having a nice body without the baby face that early 20 chicks usually have.