Re: Favorite villain of the trilogy?
I'd say Stane, just because of Jeff Bridge's performance. One of the great comic book movie villain performances I've seen.
2nd but close would be Killian. What I loved about it, was he wasn't seeking revenge about Tony. In fact he thanked Tony for giving him the motivation to make himself more than he was. He only needed Tony because he had the stabilization formula for Extremis.
"You have a metal arm? That's awesome dude!"