Tony Stark's Hulk-Buster Iron Man. This armor is the beast to mess with. As the name implies, it is designed with one goal: Stop the Hulk when he steps out of line. Sometimes it works, other times it doesn't.
I like it the most because it really shows the vulnerability of Tony Stark and that not all of his ideas are full proof. In World War Hulk Tony took an upgraded version of the Hulk-Buster and still got the snot beat out of him. Of course Tony wasn't to be outdone and later blasted the Hulk to bits using orbital gamma satellites, but that is neither here nor their.