4. Vulture
Who Is He? An inventor named Adrian Toomes who invented a flight harness that also granted him superhuman strength, and turned to crime after his business partner left him destitute by embezzling money from their business.
Why Would He Make A Good Villain? Since Vulture can fly, Spider-Mans advantages of agility and being able to web-swing are effectively nullified because, where ever he goes, Vulture can follow him and match him in terms of speed. Which would lead to some excellent aerial fight and chase scenes. Also, the storyline used for him in the 1994 animated TV series is refreshingly different from the usual Use superpowers to steal money/take over the world ploy as it saw him draining the youth out of people to rejuvenate his own body in order to counter the frailty of his old age. The themes of old age and mortality are rarely shown in comic book films and this would be a good opportunity to do something different but the storyline would most likely conflict with the more grounded tone of the films and stop us from taking the character seriously. And finally, using Vulture would be a good opportunity to give an older actor like Ben Kingsley or John Malkovich (who was slated to play Vulture in the aborted Spider-Man 4) a larger and more active role in the series instead of them being consigned to the background as elderly relatives and wise mentors.