Green Goblin: Which one? Harry... Spectacular Spider-Man #189 when he kidnaps his family and Peter and takes them hostage to his father's estate. Some great psychological melodrama there as everyone eats at the table while Harry in his GG guise taunts Peter in his Spidey outfit. Spec #200 is of course a close second. As for Norman? Sue me. For all its flaws, 'Revelations'. Death of Gwen just bores me these days. Nothing matches the shock of seeing Norman alive after decades of believing him to be dead. I still remember that feeling.
Doc Ock: Master Planner arc. Have not read ASM#600 yet.
Mysterio: Again, sue me. The Spider-Ben arc 'Media Blizzard'.
If we're counting ALL arcs and not just Spidey, then sue me even more, because my favorite Mysterio arc is the overrated, but still quite good Kevin Smith penned 'Guardian Devil' arc. Speaking of which, I'm getting sued so much, I better get Murdock to represent me (that was terrible).
Electro: ASM#425
Shocker: That Howard Mackie arc where he made Shocker a badass, instead of a loser. It was during the Joey Z fiasco. Yeah, that. That's about the only halfway memorable storyline that loser has been involved in (for clarity's sake, I'm talking about Shocker, not Howard Mackie
).
Chameleon: Either 'Pursuit' or that Paul Jenkins arc where he jumps off a bridge (Webspinners #10-12?)
Sandman: That Peter Parker:Spider-Man story by Jenkins. He's falling apart because he got bit by Venom. Then he goes down some storm drain, while telling Peter to go pet his dumb kitty or something. What can I say? It was touching.
Venom: The one where he visits Aunt May's home.
Scorpion: The 13 part Marvel Knights: Spider-Man arc by Mark Millar. I totally loved this story-line and hate when people rag on it. There was so much palpable tension in some parts, you could cut it with a knife.
Lizard: Um, 'Torment' that story that kicked off adjectiveless Spider-Man.
Vulture: Dude, you already asked about Vulture! You got some Vulture man-crush or something?
t:
Hobgoblin: Anything before 1986. lol
Hydro-Man: Bwahahahaahahhahahahahahaha.... Memorable Hydro-Man arc??? Oh, that's a good one.
Rhino: The 'Sensational Spider-Man' arc where he hulks out because he is numb and can't feel anything through his suit. Peter takes him out with a live-wire which finally puts him in agony and before he passes out he says "thanks."
Kraven the Hunter: Obvious.
Kingpin: Back in Black.
Alistair Smythe: Invasion of the Spider-Slayers. And that was only "just okay."