I would have to say Iron Man. S3 was kinda fluke to the whole Spiderman series. Iron Man was original and gave a great story line, unlike S3 that was just the same thing fight a boss, lose Jane, get back Jane, win the boss fight.
Spider Man 3 had so much stuff that should just be cut out. The scene where the reporter head pays $50 for a roll of film is just worthless. And then the ending is horrible. There wasn't any loss or struggle. The evil people might as well have been nuked. Ironman, although it's a bit generic, is my pick.
This is one of those times when you say" No Brainer." Iron Man was original, had him make his suit, had a bit of this and that, and the villain didn't want domination but was just plain greedy. S3 was a disgrace to Marvel and the Spiderman Series