I like the first one the most, and that's primarily due to Dafoe's performance (stupid green Jack Nicholson mask aside). I'm not so fond of Kirsten Dunst's Mary Jane, though, anymore; she's just doesn't do the character any justice at all (and that shade of red they dyed her hair is atrocious).
The second one's okay, though I think Doc Ock really should have been more villainous like his comic book counterpart.
The third one is a real mess. There is a good movie somewhere under all the crap, though, so I don't hate it.
The reboot was a complete disappointment. Everything about it -- Peter's characterization, his relationship with his uncle, his relationship with Gwen, the Lizard's design -- was so horribly, horribly bungled. Whatever problems Raimi's films had, they're nowhere near as bad as the ones with this one. I'm not going to even bother with the sequel -- that's how bad the taste this movie left me with was.