When we deal with scrappy tops, the advice is usually that a light-to-medium slate blue/grey or a beige is usually the safest bet.
That's why I usually am using those colors as my piecing threads too, if I match colors with my vision issues I can't see the seams, and with the amounts of different fabrics I use, I'd be changing thread every 2" seam... and that is not how I wish to do things!