What type of boxer ages the best?

The guy who doesn't do drugs, drink or get let his weight balloon between fights. Good genes also help, some dudes age quicker.

 

The most adaptable to change. Leaving aside the deterioriation caused by multiple concussions, all fighters will slow down and lose a step as they get older. The fighters who prosper into the advanced stages of their careers are those who can make the necessary adjustments to their style to minimise the effects of declining speed and reflexes.

If you look at the most successful 40+ fighters in history, there is a mix of styles.

 

tyson was a puncher and technician was over the hill at age 30

 

Hopkins/ward type technician

 

Technician

Fighters who while they may be somewhat gifted athletically, their main gifts are mental, and technical, neither of these erode with time, and the former arguably gets better.

See - Juan, Hopkins, I think Floyd falls into this category, though he obviously possessed exceptional physical gifts in his youth, to the extent the other two did not. Also of course, the less punishment taken, the better.

Combine their fistic skill with what will generally be a high level of adaptability and you have a recipe for longevity, and other words that almost rhyme.

Pep is another good example

 

That one that doesnt have life debilitating habits outside the ring.