1. Field of Dreams
2. Eight Men Out
3. Moneyball
4. The Sandlot
5. Major League
6. Bull Durham
7. A League of Their Own
8. The Natural
9. Little Big League
10. Major League II
11. Sugar
12. Fever Pitch
13. Trouble with the Curve
14. Mr. Baseball
15. The Bad News Bears
Note: These are only movies I've seen. And if I've seen it more recently as well as more often, I'm probably going to rank it higher. I'm far from a movie critic.
I do feel like you almost need to break-up the list between drama and comedy (fun) movies -- Golden Globes-esque. I don't think anyone is going to put Little Big League at #1, but it can still be the most enjoyable for some.