Spider-Man 3

Great movie. Not an awesome movie like 2, merely great like 1.

The Raimis should have left Venom for movie #4, and stuck with Goblin II, Sandman, and Black-Suit Spidey. Woulda left room for the proper amount of drama. Here's how it woulda gone down:

Goblin 2 never gets the amnesia. The hatred for Peter festers, but Harry gets his butt handed to him by Black-Suit Spidey. Harry teams up with Sandman, who didn't defeat Spidey, but did get away.

Motivation for Sandman? Goblin pays for Sandman's daughter's medical bills, in exchange for capturing Spidey for Goblin to kill.

Black-suit Spidey takes out Sandman, handing him over to the authorities after torching him into a glass statue somehow.

Final fight? Goblin takes Gwen Stacy (Black-Suit Peter's new GF) to the bridge. This time, it's Peter's symbiote-powered overconfidence that causes him to try to snag Gwen with web... and snaps her neck. (And the fans cheer, not for her death, but for her comics-canon demise.)

Overcome with rage (feeding the beast), Peter attacks Harry, eventually killing him. This ends the dramatic tragedy (and trilogy) that is the life of Harry Osborne.

He realizes what he's done, and goes to the church, where the bells rid him of the symbiote... which drips onto Eddie Brock. Murderous grin, fade to black.

Movie four is Venom. Possibly Moonwolf or Lizard, both of whose stories are ready to go in the next chapter.

Oh well.