What color should I dye my future ghost roots

I'm wanting to dye my hair a purple black and will be doing ghost roots per suggestion of my my hairdresser but can't decide what color to do for said ghost roots I'm either wanting to do lavender or indigo the pictures are my inspo for the rest of my hair color and what my hair looks like now it's a faded blue black with my natural color coming in some spots I'm also open to any other color suggestions for the ghost roots