There is no best age as we live life backwards. Hence the great philosopher George Carlin's Theory:

I want to live my next life backwards:

You start out dead and get that out of the way.

Then you wake up in a nursing home feeling better every day.

Then you get kicked out for being too healthy.

You enjoy your retirement and collect your pension.

Then, when you start work, you get a gold watch on your first day.

You work 40 years until you’re too young to work.

You get ready for High School: drink alcohol, party, and you’re generally promiscuous.

Then you go to primary school, you become a kid, you play, and you have no responsibilities.

Then you become a baby, and then…

You spend your last 9 months floating peacefully in luxury, in spa-like conditions: central heating, room service on tap, and then…

You finish off as an orgasm. I rest my case.