Put me down as one that prefers IM3 over the other two. Not that they're bad, I just find number three to be the more entertaining and rewatchable for my tastes. Also, unlike the other two the third act felt like an actual culmination of the character and plot, whereas with the first two it wasn't as tightly written, and just sort of petered out into a big CG-fight. Yeah, 3 had a "big CG fight" too, but it just felt more connected to the characters and plot, and was way more inventive.
I'd even go so far as to say that it's the only one of the three that has
fun and memorable henchmen. Raza was a red-herring villain, while IM2 couldn't seem to make up it's mind as to whether Vanko was a henchman or a villain from one act to the next. Savin and Brandt on the other hand had just that right balance of threat and charm.
Also I will never cease to find Trevor to be a gift to the franchise. Not just for the twist itself, but how certain people lost their ever-loving minds over it. Priceless!
The villains in all three Iron Man movies desperately wanted to be Tony Stark.
I don't disagree, though I would say that I find Killian was easily the more interesting of the bunch. Stane was just greedy and entitled, Vanko was . . . I still don't really grasp what his motivation was beyond some half-baked inter-family blood feud. I mean really, what even was his endgame after doing away with Tony? To sell his father's original version of the arc reactor? To become a Ten Rings super-merc? It's not exactly clear. Hammer was just a cartoon character. A very entertain played cartoon character (Rockwell is always fun to watch), but a cartoon character nonetheless. Killian on the other hand has a little more nuance . . . not a lot more, but still. He's also the only one with a legit grievance against Stark.