Backstory wise Carnage and Mysterio have always been my favorites. There would be amazing as the main villains. Venom and Carnage in the same story would also be amazing if they do it right. They smurfed yo Venom last time.

I would like to see Shocker in a film only because he is charismatic and easy to pull off as a sub plot to connect to another villain but there is no way he can carry it as the main plot. I would prefer they just stick to one villain.