Correct me if I'm wrong, but doesn't American constitution apply only to US' citizens? Even in the ideal case, were it to perfectly protect Americans from three-letter agencies' weaseling, it offers absolutely zero guarantees for non-citizens, which is 95% of world population or so. Americans could pressure USG to stop spying on foreigners, but why would they? I don't see any incentive for an average John Doe to do so.

So, overall, there's not that much of a difference for most of the world. One might even argue that for outsiders Chinese relatively stable direction and autocracy is marginally better than American flipping every 8 years, since it allows you to better assess threat profile.

Edit: added a bit about assessing threat.