Any combination of black, white, and red seems to be popular- my LQS can't seem to keep them in stock anyway. Consider 5 - yard bundles with patterns for 5-yard quilts. I love having the fabric chosen for me. My LQS has a section with just those bundles - the red/white/black and any batik collection seem to be big sellers. Good luck!
Greys and yellows also seem to be big - anything with grey.