I think to get the best of males and females in the Delaware breed, you'd have to breed separately for the best females and best males, I believe that's called double mating system? I've read that as well as had breeders tell me that about the Delawares.
Obviously, you have to start somewhere, or else you'd be culling and culling and culling and never start breeding, even if you have a bird with a couple minor faults, right? If you wanted to start with the absolute perfect bird, it would take years and years to get your very first flock sire, if ever! Get one with the best body type you can and decent comb and coloring, even if not perfect, and go from there would be the best course of action, in my opinion. Kathy's Oliver is awesome in that regard, at least to my eye. Isaac has produced lots of huge deep bodied sons for folks, but I wish I'd had slightly better hens for him, though I have a couple really nice ones, just not quite "there". His daughters usually have fabulous tail black. I decided not to continue with the Delawares, as far as actually breeding them, or I'd be hatching out more just to accomplish that. I think this is a challenging breed to get right, especially since it's coming back from near obscurity and there isn't much great breeding stock out there.