Personally I think men have two peaks, one at university i.e. 18-24 years, where they probably hit their peak physical shape and have grown out of their teenage appearance. But then from 35-45 years we develop a more mature manliness which I think many women find appealing. Although physical shape goes down, ruggedness and maturity goes up and this also has appeal. Think Don Draper, Clooney etc.
Between 25-35yrs is just an awkward stage where you're transitioning between the two.