Here are two walnut wood sets I'm looking at selecting. Wow are they nice. I'm leaning towards the English walnut. But the figure on the Black walnut is so unusual. Since one hardly sees the backs when playing, the side wood is what one looks at most of the time.
Since you broke the ice, I'd go with the black walnut as well. I love the more dramatic contrast in the grains plus the added dimension of the "waves" of grain. Oh beautiful!! I think the black walnut looks warmer and more interesting.
This is like when your wife/girlfriend says, Which of these two outfits should I wear? That one. What's the matter with this one?
Either set will be beautiful once it's finished. I like the shading of the English walnut, but we see a lot of vertical sapwood in koa ukes. So I'd vote for the unusual look of the black walnut.
I have a black walnut octave mandolin, but I would not have kicked it back had it arrived looking like the English walnut shown in the photo. Truth is, IMHO, finish options will make more difference in final presentation than the currently viewable subtle differences in nekkid wood.