Stealth game with the smartest ai?

I was very very impressed with the ai in mgs 5 ground zeroes. On hard difficulty the distance from which they could see me was just like it would be in real life especially in the daylight missions. Also the response of the ai influenced the ai around the entire base due to their communication devices. Overall very impressive.

The Last of Us had some interesting stealth AI. While the infected were pretty much blind and not terribly observant, human enemies were very hard to get past. Also, if you threw an object to distract enemies (infected or otherwise), they would -never- return to their old patrol patterns and would stay on high alert indefinitely so you had to use this option very sparingly.

-Byshop