This is really a regional thing..In the south RW is quite poular..up here in the abyss..er..New England... Left wing is much easier to find at the shops..very few carry RW...We have every color gateway makes I think in LW at my local shop, but about 4 colors in RW for those who want RW..most shops don't even carry a few colors of RW. And even with vanes everyone fletches LW it seems.

As to the original question..Helical..regardless of wing...just make sure if you are using feathers to get RW clamps for RW feathers and LW clamps for LW feathers