Any man of legal age.
it really kicks in just before 30.
Well that all depends... For me i feel im in my prime now. And im 16. Everybody is different.
From my experience with my girlfriend they will get pleasure at any age as long as they want it
A woman's sex drive is on top in her 30's and there's one change when she hits menopause but it's also individual and depends on where she is in life. Having children and a busy work- or home life...