Hugo nominee: Slaughterhouse-Five by Kurt Vonnegut, 1970
My view: I suppose a hypothetical hard SF purist will refer to this as slipstream (o, Mother no!) and consign this to the non-SFnal rubbish heap instead of calling it the antiwar fable dressed up in SF clothing that it obviously is, but consider this - any number of Hugo nominees can be considered antiwar fables; the fact that they're encased in much more traditional forms of SF is probably the reason why they're not distastefully squinted at in a similar fashion. I suspect Vonnegut left organized SF more for that reason than any other. I wouldn't have, but a writer has to do what he or she thinks makes sense to their careers and artistic tastes. It's obvious Vonnegut apparently needed to do just that.
Nuggety?: You're kidding, right...?