Dry.
Maybe I do not have enough experience but 80cts vs $6 (basically my grain bill for a 5gal batch), I go for dry and so far, I never had a problem, no rehydratation, just pitch the dry yeast.
So I do not see why adding 30% of cost on my batch just for yeast, I believe (tell me if I'm wrong) that the grains/hops are the one responsible for the flavor mainly, not yeast. I known more people claim the opposite (starting by the white lab website...).
I used liquid twice and I did not see a difference (except it spahed on my hands when I opened it up)... I guess the ultimate test is to make a batch and then split it using dry in one primary and liquid in the other primary!