I prefer Iron Man 1 mostly because I loved the science nerding and suit design But Iron Man 3 aren't far behind sine I think it gives Stark a lot of character beside the joke cracking genius, and the Mandarin actor was hilarious.
The way the poll results are shown after I've put in my vote is exactly how I rank the Iron Man films: 1, 3, and 2. I'll always enjoy Iron Man 2, but I felt I had more fun with 3; especially during the climax. Plus, surprise Fin Fang Foom cameo (which is how I'll always refer to one of the characters in the movie as)
For me none: Tony Stark is a douche, reveals the one secret publicly that no one should reveal publicly, creates a weapon that (in part by defense contract) belongs to the government, plays a tease-please romance with Potts constantly wavering from "I don't give a wrinkled wallet" to "I love you more than spit", And in the end, HE DOESN'T LEARN A #THING!!!!!!!!!!!!!!!!!!!- HE'S JUST A(N ALCOHOLIC) DOUCHE IN A HIGH-TECH, FLYING, RAY GUN!!!!!!!!
...............But if I had to choose, I'd choose the first one; the ending pushes Stark from self indulgent to narcissistic historic personality disorder, but at least it makes the character mildly likeable...