They are simply different animals. I like the four yard box pleated kilt better in warmer weather, and find them easier to manage in general with sitting. They do tend to wrinkle easier, and so look less crisp more quickly than does an eight yard knife pleated kilt.

The knife pleated one is what most people think of when they hear the word "kilt", and is generally more common. They are really nice for cold weather, and they do swish better.

I like both. One more eight yard knife pleated kilt, and I will have an even number of each.