First of all, he’s got an absolutely ridiculous costume that is a fashion nightmare. Cheetah-print pants, zebra-stripe belt and cuffs, and a lion’s head vest with no shirt, plus the giant 70s stache and soul-patch. You couldn’t forget that look if you tried. So he passes the first test of a great villain: he’s instantly memorable. 

Second, he’s got an amazing concept – a big game hunter who insists on killing hand-to-hand because anything else would be insufficiently manly, and who runs out of dangerous animals to kill with his bare hands so decides to hunt…Spider-Man. He doesn’t have some stupid grudge against Spider-Man because of something in their past, he’s not a career criminal or mobster – he just wants to prove he’s stronger than Spider-Man. There’s a purity and simplicity (and to be honest, irrationality – I mean, why Spider-Man and not the Hulk?) there that’s refreshing and novel. 

Third, Kraven shot Spider-Man with a tranq dart, buried him alive, put on Spider-Man’s costume, and then went out to prove that he could out-Spider-Man Spider-Man…and actually succeeded, saving Mary Jane Watson’s life and single-handedly defeating Vermin (something Spider-Man hadn’t accomplished). When Spider-Man escaped from the grave, Kraven refused to fight him, having proven his point, and promptly confessed and committed suicide. 

What I love about that is that Kraven’s ultimate villainous scheme is that he pulls off a permanent victory over Spider-Man that got into his head and affected him profoundly – you don’t get over being buried alive lightly – in a brilliantly orthagonal way. He doesn’t kill Spider-Man or one of his loved ones (looking at you, Green Goblin), he doesn’t clone Spider-Man or try to merge with Spider-Man or any of that nonesense. He beats Spider-Man thoroughly by out-doing him and then goes out on top so that Spider-Man doesn’t even get the chance for a come-back. 

So there you have it, the basics of a quality villain: good look, good concept, memorable scheme/victory.