I hope Kirsten is out. She had a coke problem during Spidey 3 and it showed. She also hates doing the movies, and who seriously wants somebody like that screwing up your work?
I like the idea of lizard a lot. Kraven isn't a bad idea either. I'd love to have a real Venom movie with Spidey, but that's done now. So that seems like a good route to take. Electro wouldn't be bad either.
Out with Mary Jane. Bring on Black Cat. That's my two cents. Seeing Harry and Peter work together was one of the highlights in an otherwise dreadful film. I want to see another team up.
EDIT: I just had another idea. What about Scorpion? Just saying. Another villian that might work.
I don't think Scorpion would work...in the films they haven't really developed JJJ's hatred of Spider-Man. And I hope they don't break up Pete/MJ, I like the fact that so far she's been the only girl for him.