First rule here is to keep the discussion seemly, I know this is an emotive subject.
Godwins are an immediate 10 point penalty, so let's leave them for the high-school debaters.
Second rule is, that for the purposes of this discussion, eugenics means just this and no more:
Eugenics is the study and practice of selective breeding applied to humans, with the aim of improving the species.
Not ripping foetuses out of mothers because they have don't conform to genetic perfection, but just the selection - and removal of genes - in an effort to design a human race.
Scientifically, this is quite feasible, and we have centuries of proof in breeding animals to prove that it is clearly possible to build a healthier species by selectively breeding a population to order.
Morally, I think a strong secular case can be made for improving the human race physically and maybe intellectually.
Historically, I think we do it by default as a by-product of our evolved genes anyway, where we are conditioned to look for a genetically-suitable partner and while it's a bit haphazard, the idea is basically the same. China does it with the one-child rule, sperm banks do it with screening of candidates to a criteria, countries with arranged marriages have it done by parents and social heirarchy does it by limiting children to potential mates of the desirable social group/class.
Realistically, the only problem with eugenics is the political one - who makes the decision on which genes are de/selected for. Once it becomes a doctrine, it is open to abuse, so the idea can never be used on a wide scale, despite the clear benefits to mankind as a species.