Really, the villains I would still like to see most are the Lizard, Electro, and Mysterio. Lizard because he provides a new challenge on both a personal and physical level (yes, I am aware of the father figure turned villain thing), Electro because he is a classic villain who would not look similar to a villain we have seen already in the SM movies, and Mysterio because he could provide some excellent on screen effects (since he is an FX master and could show us pretty much anything) and would be different from anyone we have seen already. Not saying these are the only villains they have left, but after these guys, a lot of Spidey's villains are not as impressive, since they have similar powers or looks from an effects standpoint. Look at Scorpion. After seeing the Lizard on screen, his tail is less impressive. Hyrdo Man is basically the water Sandman. Shocker is a less impressive Electro. Hobgoblin is another goblin, etc. Villains like the Vulture, Kraven, or even Carnage (though I am not a fan of him, since he is a weak character and couldn't carry a movie himself) would be good for use also.