The structure of the company mostly selling service to a foreign country
Typically an LLC is more practical for a small business operation, as it is flexible, easy to manage, and separates your business from your personal assets much like corporation does, without the added tax filing complexities. A sole-proprietorship would only allow you to operate under a fictitious name, without offering any personal asset protection, or the ability to register in a different state or jurisdiction. (In many states, such as New York, DBA's are registered on a county basis).
It's very common to see companies register remotely in business-friendly states such as Delaware or Wyoming when possible.
I'd like to share an answer posted by our tax expert Wray titled 'Forming Internet Service LLC and Nexus', which may help you make the best decision for your personal situation.