I personally like the red! IMO, the black has nothing to tie it in with the blocks. White would be my 2nd choice. Seems to me the blue dulls the quilt too much.
Edit: I wonder if a slightly narrower sashing would make a difference? Seems to me that the sashing width almost overpowers the very intricate blocks. Maybe a red sashing width more in keeping with the width of the red in the blocks?