I vote for the white. The black just "jumps" out at you. The white looks more like it's part of the blocks.

Most def, black.

I vote black.

I like the white.

I like the way white lightens it up!

I'm not very partial to black at the best of times, so a black sashing doesn't really appeal to me.

I like the white but maybe a bit narrower?

The black sassing makes your fabric pop.

I vote for white!! Seems to combine instead of separating the blocks, IMHO.

I like both too...have you ever thought of mixing it up? Some white and some black? Keeping your red cornerstones? Just something else to think about.