If you're asking that question, and really aim to write crypto safe from the NSA, then I think you have a lot more learning to do. Just naming off a different mode isn't going to cut it.

The Matasano crypto challenges seem to be popular lately. That would be a decent place to start.

Your implementation is vulnerable to MITM attacks. That will be the case no matter which AES mode you choose.

You are on the tip of the greatest problem with modern cryptography, which is that there is no real way for widespread confidentiality to be created without trusting a third party such as a CA. But once you trust a CA, then you become vulnerable to the backdoors available through the CA community (not just one CA.)

Personally, I'm hoping for a bitcoin-like protocol (such as namecoin) to create a peer-to-peer trust network for distributing public keys.

PKI is only useful when the root are truly trusted and tightly controlled (or even supervised with highly transparent audit programs). The current generation of Internet CAs don't even come close - they are not trusted by anyone except themselves, and they sure are willing to take your money if it'll make you feel better!

Wait, you're trying to beat NSA by writing your own crypto? This is worse than useless :), all you'll do is flag that communication for further research (which the NSA will then break within a couple of hours if need be), at least with plain text you'll stay in the noise of the masses.