I've heard and I hope someone more knowledgeable can confirm that the easiest is to incorporate in Delaware for foreigners. To maintain the Delaware corp you have to pay a franchise tax on the amount of stocks you have issues (for C-corps at least). I'd have to look it up again but up to 5000 shares it's 75$ a year. If the company is not in Delaware then you won't have to pay income taxes.
Delaware franchise tax is done two different ways. You pick the method you want to use. The first method is based on the par value of outstanding stock and the second is based on net assets of your company. Delaware will send you a bill using the method that maximizes the franchise tax. You should use the method that minimizes the franchise tax. You can have 10,000,000 shares outstanding at a par value of .0001 and still pay, essentially 0 in franchise tax (or the necessary minimum) if your assets are low.
There's actually quite a lot of helpful information and a pretty good introduction to incorporating, shares and taxes here too: http://www.tannedfeet.com/c-corp.htm
