i too think Lizard and Kraven would be good to see.
infact, i can already come up with a storyline. let's say we are introduced to Kraven first, as he hunts down big game animals. then somehow Dr.Connor transforms into The Lizard. that's when Kraven gets interested and wants to hunt The Lizard down. but then Spidey comes in and tries to protect The Lizard from Kraven, since he knows it's his friend Dr.Connor. but ofcourse, The Lizard wouldn't give a crap, and still try to kill Spidey and Kraven. it could be an awesome 3-way battle. and so on.
infact, i can even see room for foreshadowing of Carnage and Rhino in the future flicks.