Originally Posted by
Revolutionary_Jack
Ditko gave unto the world: the Chameleon, the Vulture, Dr. Octopus, the Scorpion, the Lizard, Mysterio, Kraven the Hunter, Electro, the Sandman, the Green Goblin, the Spider Slayers. Also Molten Man, who has been minor but not entirely forgotten. And Crime Master, a one-shot villain who was so memorable that Conway based Hammerhead and Tombstone on him. I will say that I don't think later writers have built properly on the foundation that Ditko laid out. Some have been served better than others.
Romita Sr gave us Kingpin, Rhino and the Shocker. Who have all been fleshed out by other writers with Kngpin in particular becoming in the pages of Daredevil one of Marvel's greatest villains eclipsing his appearances in Spider-Man by several 100 miles. Shocker has been used well and used badly but his design and gimmick is iconic and sticks. Rhino is the best of the three.
Conway gave us: Hammerhead, Tarantula, the Jackal. Tarantula has kind of endured as a semi-decent minor villain, while Jackal has to rank on the list with bad villains in a great story (The First Clone Saga) sweepstakes (alongside the likes of Doomsday and Bane). Later Conway came back and gave us Tombstone, who is better than Hammehead in my view and whose appearance in the PS4 game stole all the scenes.
After that, you have a lag, Wolfman gave us Black Cat, Dennis O'Neil gave us Calypso and Hydro Man, Stern gave us Hobgoblin, Defalco gave us the Rose and also Silver Sable, then Michelinie delivered the biggest Spider-Man villains since Ditko and arguably the biggest villains ever -- Venom and Carnage. Then JMS gave us Morlun. BND and Slott have us Mr. Negative, White Rabbit, Overdrive, and Screwball.
We can't forget the villains unique to Spectacular the likes of Hypo Hustler, the Spot, and the Sin-Eater (and also Tombstone who first appeared there).
In terms of new villains versus old it kind of depends on what you mean. In general a villain is best served if they are introduced with a story that's instantly a classic or great issue. Like the reason Venom is so big is because he was built up well but also his reveal and introduction is one of the all-time great Spider-Man stories and moments. Whereas that's not the case for all new villains.