Incorporation V's Sole Proprietorship--Unless a business is very small, there is really no question that you should incorporate. From a legal and financial standpoint, this is a much better choice. It also will give you something you can sell far easier should you ever want to.
As for which format is better--C-Corp, S-Corp, LLC or any other form of structure--that question is answered differently in every state; even some county or cities will make the answer different. Your marital status and desire for estate planning also impact the answer, so the best advice I can give to you is to find a great attorney or accountant who specializes in structure and planning.
All the Best,