In my opinion, this tartan and tartans like it (Stewarts, for example) look really good pleated to the horizontal stripe (i.e. hide all of the vertical lines in the pleat so that only the horizontal lines show). They're all relatively busy designs, and this tends to help darken it a little.

I also think that it depends on other factors. Do you want a dark-ish or bright-ish kilt? horizontal stripe looks darker, and white stripe is brighter. Yellow or sett could be right in the middle. I also think that horizontal stripe pleating makes the kilt look wider, and thus suits people of narrower build like me. On the other hand, any vertical stripe will make it look taller, and thus fits people of larger build. Sett pleating seems to fall directly in between, making the kilt look more even.