I like both of these movies but I think I will be voting for The Godfather Part 2. It added backstory to the first movie while also moving forward with Michael Corleone, with him running things instead of his father. It also kept the feel of the first movie which I thought is an important thing that sequels should try and do. The 3rd Godfather had a very different feel and that was one reason why it doesn't really mix well with the other two of the trilogy.
300 was a great action movie, and was a lot more entertaining then it would seem to be. I think the unique style and setting of the movie sets it apart from other action/war movies, and makes it a memorable film to watch. But compared to the Godfather 2 it is just a bit too simplistic.
