It depends what your looking for in your mail pieces - I personally feel the items for leatherworking are much better for a hunter/shaman.
Plus the plans are much easier to obtain, I think.
But it depends on what type of items you are truly looking for your shaman. Or if you wish to craft items.
If you only care about the armour take up the leatherworking, if you would like the extra perk of weapons take up the blacksmithing.