Unless there are other reasons that would cause a corporation to make more sense to you, there are very few reasons NOT to form a LLC. You are taxed the same as a sole proprietorship, have minimal filing and other costs, and obtain protection from any personal liability.
To be clear, when you register a fictitious name, you are not "incorporated." You are merely telling your state that you are operating a business under a fictitious name - no more, no less. You are not creating a separate business entity by registering a fictitious name alone.
Lastly, you typically will not see any tax benefits by setting up a corporation, but you should speak with both a tax and legal advisor to best determine what entity makes the most sense in your particular situation. There is no one size fits all.
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Somerville, NJ 08876
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The Legal Considerations of Starting an Online Business