Last season Inter Milan were champions and AC Milan were runners up but there was a lot of difference between champions and runners up. Inter Milan won by a lot of points, on the contrary, Milan had less points despite being the runners-up. However, I think AC Milan will improve their performance significantly in the next season and they will have a tough competition with Inter Milan.
AC Milan drew against SK Rapid Wien, won the match with Manchester City, and lost the game with Real Madrid and Barcelona. So the only renowned club they won was City. From the above results, we can assume that their performance was average. The club has recruited players like Strahinja Pavlović, Emerson Royal, Álvaro Morata, Álex Jiménez and others to fortify the team this season. Paulo Fonseca the new coach of AC Milan is not new to the Italian League since he was once the coach of Roma where he led them to fifth and seventh position. He also had relatively impressive performance in Ligue One where he led Lille to fourth and fifth position and also guided them to the Europa League.
Inter Milan still has better chances of dominating the Italian League, since they were able to retain key players and also the best coach Simone Inzaghi. AC Milan will take some time to experiment with players and tactics but Inter has an already established team.