It all depends on what size quilts you like to make and what style you have.
I like big lap 50x60, extra big twin 60+ x 100+, and Cal King 120X120.
I also like a scrappy look so consequently I own a lot of FQ and then buy yardage for borders 1 1/4 to 3 yards and yardage for backing 4, 6 or 12 yards.