Monero is.

So you think if a notorious terrorist or whatever moved millions of dollars through Monero to fund a terror attack, American or other intelligence agencies wouldn't be able to identify the transaction?

It could be done truly anonymously when up against the full weight and might of US, Western, Israeli etc intelligence budgets and methods?

Well the sender, receiver and the amounts are all hidden, so yes.

I should still note that it isn't a magic bullet, and that things you do in connection to the monero blockchain can obviously still give the authorities an idea of what you are doing.

Would it still be hidden if a government identified servers hosting the network, seized them and forensically analyzed them including having access to potential zero days in encryption tools, backdoors in algorithms, and supercomputers?

Etc etc. My point is that anonymous is an ideal, not a absolutist reality.

You could convert Monero ou Zcash to Bitcoin at an exchange before paying. I don't know which exchanges currently allow to do that without verifying your identity, though.

Doesn't Monero focus on differential privacy? Meaning you have plausible deniability not anonymity. Where as something like ZCash you have to trust the seed. Did things change?