It depends as with age, there is maturity. But as far as natural gifts and recuperative powers, youth has its advantages. An example being, Muhammad Ali was far better in his peak years, 1964-1967, he had all of his natural gifts, he was not vulnerable as he was on his comeback in the 1970's, where he took too much punishment. Bernard Hopkins was much better at an older age, he gained experience in the ring, used his various bag of tricks in winning what appeared to be difficult bouts. I think it depends on the individual.
Yeah he got better and better after his slow UK start. But you want to have seen him in Nigeria before he came to blighty...
Micky Ward started gaining momentum later in his career, Jersey Joe Walcott obviously, can’t really think of to many others off hand, good question bro