During the cold war, spying actually helped prevent war. I am absolutely fine with the USG spying on foreign governments, militaries, and to a lesser extent, specific war-related businesses (arms manufacturers, potentially energy and logistics companies, etc.) -- the spying on civilian firms should be firewalled off from any potential commercial utility, and should be purely passive and primarily through open sources, but even that seems potentially legitimate.

Spying on purely private people through blanket collection is wrong, both of US citizens and foreign citizens.

I'd be comfortable with foreign intelligence services operating under the same rules.