"Best" pretty clearly means higher IQ in this context.
The fact that the practical engineering required to accomplish that will involve setbacks, failures, costs, and suffering doesn't mean that we can't define the goal.
Intelligence genes discovered by scientists The Telegraph, Dec 21 2015 https://www.telegraph.co.uk/news/science/science-news/120617...
Many similar articles, not all about the same discovery, at this DDG search:
https://duckduckgo.com/?q=genes+for+intelligence+found&t=ffa...
Basically just noting that we now know at least some of those genes.
Many more will be found. Some will have other deleterious effects, and we'll figure that out too. The cause-and-effect of genotype and phenotype will be slowly decoded. It's just a matter of time; there's nothing unsurmountable here at all.