That's actually a problem I must constantly resist xD.
I have a litter that will be a week old tomorrow with an awesome little one, then again, I'm a sucker for anything with huge patches of color, especially on the face.
I've got a waiting list that spilled over on my last litter (too many people and not enough babies xD) and only three babies with this litter, but this baby, omg x_x. So tempted to keep it.
Plus I think it's a little girl, it's got a little explanation point with a dot on top lol the other two babies are just two dots like
:
I had one in the last litter that had half a split face but it turned out to be a buck, so I didn't keep it, but I may not keep this one either. I dunno :|
So I am definitely one that would keep one based on what they look like xD.
Anyway, I'd say if you want to keep the lineage of that particular buck alive and don't have any of his other offspring, you should keep her, it's entirely up to preference.