Whose a better Don?
My vote goes to Vito. Not only was he a brilliant man, but he was always able to keep his wife, whereas Michael has a rough history with Kay, and they end up getting a divorce.
Altough Vito demonstrates his intelligence in a number of scenes throughout the movie, the scene that gives me the best, and clearest understanding of Vito's intelligence is when Michael and Vito are in the Courtyard discussing about their plans. Vito is the one that is credited for figuring out all about the traitor and this saves Michael's Life