6-9-12 has been my choice for the last few years.
3 meters is a big gap, but it does make choosing a kite size very easy. And cheaper too.
If you want to ride a wide wind range, a 4 kite quiver is better.
For example,
Sometimes overpowered on the 6,
Sometimes the 6 is a bit small and the 9 too big.
Sometimes the 12 is too small,
Maybe I'll go back to a 4 kite quiver.............. 6-8-10-13
Or move to Maui, where I think I could be happy with a two kite quiver.