US citizen living abroad: Which is best state to incorporate in?
The only limitation I can think of for you and your partners in organizing a US-based business is S-Corporation Election - you cannot do it, since one of the partners is not a US-person (all shareholders/members must be US citizens or resident aliens).
Other than that I see no reason why you wouldn't form your company in Delaware (and probably choose an LLC and not corporation, as corporation is a double-taxation entity). Also, you being from California and your second partner living in California is not a reason to form your company in California, unless you plan to establish physical presence for your business in California. From your business description I deduct that this business will not have any real connection to any state, so you are free to choose one of the incorporation friendly states, such as Delaware or Wyoming, as the state of formation for your company.