I've been wrestling with this problem with my CR-10S with an e3d v6 hotend for quite a while now. The layering is quite inconsistent in the X and Y directions (and appears to be about the same in both).
I've gone through the hardware with a fine-toothed comb, and I am confident my belts are tight, axes are secure, and bolts are snug. I'm less sure about settings.
Changing speed, acceleration, and jerk does not change anything. Changing temperature does not change anything.
This was printed in Hatchbox Black PLA at 195C/60C with a 100% flow rate at 50mm/s.
Note: the print looks good from the side, but horrible from this angle.