I use the 'Christmas tree method' when deciding whether something will look good pleated to the stripe.

You know how you fix lights on an Xmas tree by squinting at the tree while lit to see where there are too many or loo few lights? Do the same here...

Squint at the cloth. If a particular stripe really jumps out at you, it would look good pleated to that stripe. If nothing really jumps out by itself, it would probably look better pleated to sett.

In the case of the tartan above, the white and / or yellow jump out at me. I would pleat it to one of those 2 if pleating to the stripe. If you pleat to something a different stripe, you'll have the 'lawn chair effect' of horizontal stripes.