Of all the Marvel Films made so far, I enjoyed the Spidey flicks the best. The writing and CGI are great. But the real draw for me was seeing Peter's developing social consciousness & the extent of self-sacrificing that went along with it. I especially liked the building rescue because it had Peter go in there as himself and not Spiderman. It was another moment of truth and he had no "selfish" motives there, like say, rescueing MJ. Peter felt he personally should do something and went in to rescue her, despite not fully having his powers. He towers over Superman and Batman IMHO.
Mysterio would be a cool third villain and I think some interesting mind games could be written into the script with Mysterio's mastery of illusions.