I like fir when I can get it. It is usualy him/fir mixed here. The hemlock will split more and tends to twist more but once in place it's not a big problem. Dry verses green may be the question you want to ask. Here, WA, most seems to be built green. There are some "pops" when finnished but they can be fixed a lot cheeper than buying dry lumber. If the construction is outside in the rain, dry lumber will not stay dry anyway. Have fun. PC