Honestly, I think it's an impossible question to answer in a generic sense.
Health I'd say is a bigger concern than age.
A fit man in his fifties I'd argue is better placed for fatherhood than a very unfit smoking/overweight man in their thirties for example, including in respect of life expectancy.
Ultimately I think you need to think about the person rather than the age.
Do they already have children? How old are they? How would you feel about being a step mother? If they don't why not? Late bloomer or George Clooney type?
Young parents can be shit parents - the same in reverse.
I think having a good parent for less time is far better than the alternative of having a shitty parent for longer.
All that said, I absolutely do question men having children into their sixties and let's face it, most of them that do are very wealthy with women half their age.
The trade off there is pretty clear and it's not the child's best interests that are central.